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1 IFIP IN '95 CONFERENCE Copenhagen TUTORIAL ON INTELLIGENT NETWORKS Olli Martikainen*, Juha Lipiäinen**, Kim Molin...

IFIP IN '95 CONFERENCE Copenhagen 28.-31.8.1995

TUTORIAL ON INTELLIGENT NETWORKS

Olli Martikainen*, Juha Lipiäinen**, Kim Molin*** *Telecom Finland, P.O. Box 106, FIN-00511 Helsinki, Finland Tel. +358 2040 3503, Fax.+358 2040 3251 **Nokia Telecommunications, P.O.Box 33, FIN-02601 Espoo, Finland Tel. +358 0 5116691, Fax. +358 0 5115595 ***Lappeenranta University of Technology, Datacommunication Laboratory, P.O.Box 20, FIN-53851 Lappeenranta, Finland Tel. +358 53 624 3613, Fax. +358 53 624 3650

Abstract The development of telecommunications technology and the need for more advanced services has created projects on standardization of international Intelligent Networks (IN). The standards of Intelligent Networks define IN in an abstract point of view, so it leaves the service providers the decisions on their own implementations. The first standard sets of IN are Bellcore’s AIN.0 and the CCITT’s Capability Set 1 (CS1). They define the basic services of IN, additional features such as rapid service introduction and a flexible architecture that provides future expansion to further IN Capability Sets. The standardization organisations, such as CCITT and ETSI, work hard to help the service providers to implement their IN architecture in order to be able to provide international IN services. This kind of architecture is better known as Global Intelligent Network architecture and it should be taken into consideration already in the early implementations of IN. This paper presents some history of telecommunications technology, an overview of IN and its services and some additional discussion on the future broadband IN.

Contents Abbreviations

1. PREFACE

2. INTRODUCTION

2.1 Early computers and telecommunications

2.2 Switching systems development

2.3 Turning-points in telecommunications

2.3.1

UMTS

2.3.2

MEDIA

3. COMPUTER CONTROLLED TELECOMMUNICATIONS 3.1 CCITT Signalling System No. 7

8 8

3.1.1

Network Services Part

3.1.2

User Part

3.1.3

Signalling network structure

3.2 Telecommunications Management Network

3.2.1

Functional architecture

3.2.2

Informational architecture

3.2.3

Physical architecture

3.3 Intelligent Network 3.3.1

The need for IN

3.3.2

Definition of Intelligent Network

3.4 Numbering and Services

INTELLIGENT NETWORK ARCHITECTURE

4.1 Overview of IN

16 16

4.1.1.

Origins of IN

4.1.2.

IN standardization

4.1.2.1 4.1.2.1.1

IN standards bodies ETSI

18 18

4.1.2.1.2

CCITT

4.1.2.2

Phased standardization

4.1.2.3

Structure of CCITT IN standards

4.1.2.4

Capability Set 1

4.1.2.5

IN CS1 Services

4.2 IN Functional Requirements

4.2.1

Service Requirements

4.2.2.

Network Requirements

4.3 IN Conceptual Model 4.3.1

Physical Plane

4.3.1.1

Physical Entities

26 28 28

4.3.1.1.1

SSP

4.3.1.1.2

NAP

4.3.1.1.3

SCP

4.3.1.1.4

4.3.1.1.5

4.3.1.1.6

4.3.1.1.7

SSCP

4.3.1.1.8

SDP

4.3.1.1.9

SMP

4.3.1.1.10

SCEP

4.3.1.1.11

SMAP

4.3.1.2

Interfaces between PEs

SCP-SSP interface

4.3.1.2.2

AD-SSP interface

4.3.1.2.3

IP-SSP interface

4.3.1.2.4

SN-SSP interface

4.3.1.2.5

SCP-IP interface

4.3.1.2.6

AD-IP interface

4.3.1.2.7

SCP-SDP interface

4.3.1.2.8

User interfaces

4.3.2

4.3.1.2.1

Distributed Functional Plane

4.3.2.1

Definition of FEs

33 34

4.3.2.1.1

CCAF

4.3.2.1.2

CCF

4.3.2.1.3

SSF

4.3.2.1.4

SSF/CCF Model

4.3.2.1.4.1

BCSM

4.3.2.1.4.2

Originating BCSM for CS-1

4.3.2.1.5

SCF

4.3.2.1.6

SDF

4.3.2.1.7

SRF

4.3.2.1.8

SCEF

4.3.2.1.9

SMAF

4.3.2.1.10

SMF

4.3.2.1.11

SCF Model and its relations

4.3.2.2 4.3.3

Mapping FEs to PEs

Global Functional Plane

4.3.3.1

SIB

41 41 42

4.3.3.1.1

Call Instance Data

4.3.3.1.2

Service Support Data

4.3.3.1.3

The SIB structure

4.3.3.1.3.1

Queue SIB

4.3.3.2

Basic Call Process

4.3.3.3

Global Service Logic

4.3.3.4

Relating the GFP to the DFP

4.3.4

Service Plane

4.3.4.1

Service Features

4.3.4.2

Description of CS1 Service Features

4.3.4.3

IN service modelling

4.3.4.4

Credit Card Calling

4.3.4.5

Virtual Private Network

4.3.4.6

Universal Personal Telecommunications

4.4 The IN-structured network

4.4.1

SCE

4.4.2

The function of IN

4.4.3

IN Application Protocol

4.5 Personal Communications Services

4.6 Integration of TMN and IN

4.6.1

Comparison of IN planes to TMN planes

4.7 Globalizing the IN

4.8 Future IN Capability Sets

4.9 Current activities of IN

5. CHANGES IN BUSINESS

5.1 Technology and services

5.2 Liberalization, alliances and competition

5.3 IN services

5.3.1

Benefits of IN

5.3.2

Cost structure

5.3.2.1

Initial cost of IN

5.3.2.2

Operational costs of IN

5.3.2.3

Basic call production costs

5.3.3

Service portfolio

5.3.3.1

Operators capability of offering services

5.3.3.2

Sales of service portfolio

5.3.3.3

Service development time frames

5.4 Evolution of IN capabilities at Telecom Finland

5.4.1

Pre-IN

5.4.2

Centralized IN

5.4.3

Special services

5.5 Distribution channels

5.6 Changes in enterprises

6. BROADBAND INTELLIGENCE AND MEDIA 6.1 Broadband networks 6.1.1

B-ISDN

70 70 70

6.1.1.1

Physical layer

6.1.1.2

ATM layer

6.1.1.3

ATM Adaption Layer

6.1.1.3.1

CBR

6.1.1.3.2

VBR

6.1.1.3.3

SEAL

6.1.1.4

Control plane

6.1.1.5

Management of the B-ISDN architecture

6.1.2

ATM networks

6.1.2.1

Virtual Channelss and Virtual Paths

6.2 Applications for the broadband networks

7. BROADBAND IN

73 74

7.1 Introduction

7.2 Telecom Finland BIN Project

7.3 BIN Architecture

7.3.1

Components

7.4 BIN and IN

7.5 Broadband services categorizing

7.6 Functioning of BIN architecture

7.6.1

Requirements of ATM network

7.7 Course of BIN events

79 79

7.7.1

Service request phase

7.7.2

Service activation phase

7.7.3

Service usage phase

7.7.4

Service after-usage phase

7.8 BINAP

7.8.1 BINAP-messages

7.8.2 User identification

7.9 CUSTOMER SERVICE PALETTE

7.9.1

BIN conceptual model

7.10 BIN MIB

7.11 TMN and BIN

7.12 The hardware configuration

7.13 Proposed services

8. REFERENCES

ABBREVIATIONS AAB

Automatic Alternative Billing

ABD

Abbreviated Dialling

Application Context

ACB

Automatic Call Back

ACC

Account Card Calling

Adjunct

AOD

Audio On Demand

Application Process

ASE

Application Service Element

ASN.1

Abstract Syntax Notation One

ATM

Asynchronous Transfer Mode

ATT

Attendant

AUC

Authentication Center

AUTC

Authentication

AUTZ

Authorization Code

B-IN

Broadband IN

B-ISDN

Broadband Integrated Services Digital Network

B-OSF

Business OSF

B-SCP

Broadband Service Control Point

B-SMS

Broadband Service Management System

B-SSP

Broadband Service Switching Point

BAF

Basic Access Function

BCP

Basic Call Process

BER

Basic Encoding Rules

BRI

Basic Rate Interface

BSF

Base Station Function

BTF

Basic Transit Function

CBR

Continuous Bit Rate

CCAF

Call Control Agent Function

CCBS

Completion of Call to Busy Subscriber

CCC

Credit Card Calling

CCF

Call Control Function

CCITT

Concultative Committee for International Telephony and Telegraphy

CCS

Common Channel Signalling

CCSN

Common Channel Signalling Network

Call Distribution

Compact Disk

CD-ROM

Compact Disk-Read Only Memory

Call Forwarding

CFC

Call Forwarding on BY/DA

CHA

Call Hold with Announcement

CID

Call Instance Data

CIDFP

CID Field Pointer

CLI

Calling Line Identity

COC

Consultation Calling

CON

Conference Calling

CPM

Customer Profile Management

CRA

Customized Recorded Announcement

CRD

Call Rerouting Distribution

CRG

Customized Ringing

Capability Set

CS1

Capability Set 1

CT2

Cordless Telephone 2

CUG

Closed User Group

Call Waiting

Detection Capability

DCP

Destination Point Code

DCR

Destination Call Routing

DDD

Direct Distance Dialing

DECT

Digital European Cordless Telecommunications

DFP

Distributed Functional Plane

DTMF

Dual Tone Multi-Frequencies

DUP

Destinating User Prompter

European Community

Elementary Function

EIR

Equipment Identification Register

ERMES

European Radio Message System

ETSI

European Telecommunications Standards Institute

Functional Component

Functional Entity

FEA

Functional Entity Action

FIE

Facility Information Element

FMD

Follow-Me-Diversion

FPH

Freephone

GAP

Call Gapping

GFP

Global Functional Plane

GNS

Green Number Service

GSL

Global Service Logic

GSM

Global System for Mobile communications Groupe Special Mobile

GUI

Graphical User Interface

GUS

Gravis UltraSound

HDTV

High Definition TeleVision

HLR

Home Location Register

Hewlett Packard

Intelligent Network

INA

Intelligent Network Architecture

INAP

IN Application Protocol

INCM

Intelligent Network Conceptual Model

Intelligent Peripheral

ISDN

Integrated Services Digital Network

ITU

International Telecommunications Union

IVS

INRIA Videonconferencing System

LIM

Call Limiter

LOG

Call Logging

MACF

Multiple Association Control Function

MAP

Mobile Application Part

MAS

Mass Calling

MCI

Malicious Call Identification

MIB

Management Information Base

MIT

Management Information Tree

MMC

Meet-Me-Conference

MPEG

Moving Pictures Experts Group

MSC

Mobile Services Center

MSCF

Mobile Switching Center Function

MTP

Message Transfer Part

MWC

Multi-Way Calling

N-OSF

Network OSF

N_ID

Network ID

NAF

Network Access Function

Ne-OSF

Network element OSF

NEF

Network Element Function

NNI

Network-to-Node Interface

NSP

Network Services Part

O-O

Object-Oriented

OAM

Operations And Maintenance

OC-x

Optical Carrier level at x

OCS

Originating Call Screening

ODR

Origin Dependent Routing

OFA

Off Net Access

OMAP

Operations, Maintenance, and Administration Part

ONC

Off Net Calling

ONE

One Number

OSF

Operations Systems Function

OSI

Open Systems Interconnection

OSIRM

OSI Reference Model

OUP

Originating User Prompter

PABX

Private Access Branch eXchange

PCM

Pulse Code Modulation

PCS

Personal Communications Services

PDH

Plesiochronous Digital Hierarchy

Physical Entity

Personal Identification Number

PLMN

Public Land Mobile Network

Personal Numbering

PNP

Private Numbering Plan

POI

Point Of Initiation

POR

Point Of Return

PRI

Primary Rate Interface

PRM

Premium Rate

PRMC

Premium Charging

PSTN

Public Switched Telecommunications Network

PTN

Personal Telecommunications Number

PVC

Permanent Virtual Channel

QOS

Quality of Service

QUE

Call Queueing

RACE

Research and technology development in Advanced Communications technologies in Europe

RBOC

Regional Bell Operating Company

REVC

Reverse Charging

relationship N

ROSE

Remote Operations Service Element

RTP

Real-time Transport Protocol

S-OSF

Service OSF

S_ID

Service ID

SACF

Single Association Control Function

SAO

Single Association Object

SCCP

Signalling Connection Control Part

SCE

Service Creation Environment

SCEF

Service Creation Environment Function

SCF

Service Control Function

SCF

Selective Call Forward on Busy/Don’t Answer

SCP

Service Control Point

SDF

Service Data Function

SDH

Synchronous Digital Hierarchy

SEAL

Simple and Efficient Adaptation Layer

SEC

Security Screening

Service Feature

SIB

Service-Independent building Block

SIG

Special Interest Group

SLP

Service Logic Program

SMS

Service Management System

Service Plane

SPC

Stored Program Control

SPL

Split Charging

SRF

Specialized Resource Function

Service Subscriber

SS7

Signalling System no. 7

SSD

Service Support Data

SSF

Service Switching Function

SSN

Subsystem Number

SSP

Service Switching Point

STM

Synchronous Transport Module

STP

Signalling Transfer Point

SVC

Switched Virtual Channel

TCAP

Transaction Capabilities Application Part

TCP

Transmission Control Protocol

TCS

Terminating Call Screening

TDR

Time Dependent Routing

Telco

Telecommunications Operating Company

TINA

TMN+IN

TMN

Telecommunications Management Network

Transact Processing system

TRA

Call Transfer

U_ID

User ID

UAN

Universal Access Number

UDP

User Datagram Protocol

UDR

User-Define Routing

UMTS

Universal Mobile Telecommunications System

UNI

User-to-Network Interface

User Part

UPT

Universal Personal Telecommunications

VBR

Variable Bit Rate

Virtual Channel

VCC

Virtual Channel Connection

VCI

Virtual Channel Identifier

VLR

Visitor Location Register

VOD

Video On Demand

VOT

Televoting

Virtual Path

VPI

Virtual Path Identifier

VPN

Virtual Private Network

WSF

Work Station Function

Tutorial on Intelligent Networks

changes in the switching systems and some turning-points

in telecommunications are the main concern. The concept

Preface

of Computer Controlled Telecommunications is described in section 3. It also includes signalling network history This Tutorial on Intelligent Networks has been prepared for the IFIP IN '95 conference in Copenhagen. The first version of this tutorial appeared in the second Winter School on Telecommunications in Helsinki, March 1994, and was then considerably improved for the IFIP TC-6 Workshop on Intelligent Networks in Lappeenranta on August 1994 and later for SEACOMM'94 in Kuala Lumpur, Malaysia.

After that some corrections and

modifications have been added, and the authors express their sincere gratitude for all the help they have obtained. The tutorial has been written in co-operation with Lappeenranta University of Technology and Telecom

and

development,

management

networks

for

telecommunications networks, and the need for more advanced services. The Intelligent Network Architecture (INA) is presented in section 4. from an abstract point of view. Also some future plans to expand the architecture are studied, such as Telecommunications Management Network and Intelligent Network integration. In section 5.

the

effects

telecommunications

networks

development to the telecommunications business are studied.

Some additional discussion of broadband

networks and possible broadband services in Intelligent Networks is provided in section 6.

Finland, but at present the second author is working with Nokia Telecommunications.

References are given in the text for further reading. For this reason the references given are not always the

The tutorial considers Intelligent Networks (IN) from

original ones.

user, operator and application points of view. It gives some history of the development of computers and

This tutorial has been given a permission by the authors

telecommunications networks towards more advanced

to be used freely in noncommercial educational purposes.

systems and networks that provide additional features, for example, to the normal telephony services. These computer controlled telecommunications networks and architectures

that

add

value

conventional

telecommunications networks are often referred to as Intelligent Networks. This tutorial provides a presentation of IN concepts, standards and technologies and gives a description of the situation today. Also some influential changes in the area of telecommunications business is considered. Scenarios of future developments of IN are provided. The authors of this tutorial are responsible for the possible errors and mistakes in the text and all critics and improvements are welcome. Section 2. describes the history of telecommunications and its development towards the future techniques. The

Lappeenranta University of Technology and Telecom Finland

Tutorial on Intelligent Networks

instrumentation devices. Later on, the process industry

became heavily computer controlled, and the computer

Introduction

control of manufacturing was extended largely later in the 1970's. 2.1

It was also then when the extensive use of

telecommunications networks became possible. This was

Early computers and telecommunications

supported by digital PCM-transmission technology It is almost fifty years ago since intelligence first was

(PDH-systems) deployed in the 1960´s and 1970's and

introduced in the concept of programmable electronic

modems with signalling rates of about 300 bauds. In

calculators. Since then, the development of these

those days, the telecommunications networks were still

machines towards computers has been rapid. In 1950’s

largely non-digital and did not provide bit errorfree data

computers acted as cenralized ‘batch’ processors and

transfer. Bit errors appeared very often and for this reason

there were no computer networks because of the

transport protocols at end systems and heavy link and

insufficient network technology. The programming of

network protocols between the network nodes were

early computers was very difficult because of low level

developed to minimize this unreliability problem.

instructions and primitive user interfaces. However, first high level languages such as Fortran were introduced already in 1950's. The batch processor computers worked in a simple way. They read the paper tapes bit by bit containing information presented as holes in the paper. So the Input/Output (I/O) operations of the computers were far

too

inefficient

use

the

analogous

telecommunications network that was provided at that time. The computers in those days were mainly used to

Figure -1. Transaction processing system.

scientifical calculations that needed no other I/O

In 1970’s Transaction Processing systems (TP) were

operations than instruction and data read, and a printout

taken in use in the area of banking. These TP’s

function of the calculations. So, early computers were

centralized servers located in the main office. The clients

completely in local use.

sended requests via the communication network and the TP answered them with low delay responses. Terminal

The next generation of computer technology followed from the development of time sharing operating systems in 1960's. Time sharing made it possible to have multiple I/O-terminals connected to the computer, which was the origin

local

terminal

networks

with

datacommunnication protocols. At the same time the use of computers was started in the process industry, where computers removed process measurement and control tasks from humans in the 1960’s. This meant that the I/O operations of the computers had to be developed further

networks developed to local area networks (LANs) in the 1980's and packet switched data networks (X.25) were introduced in late 1970's (Figure ).

TP’s with

communication networks was a remarkable development step and this client-server model is still in use in banking. At day time, these computer systems work as transaction processors, but at night they are used in batch processing. This is because of the daytime heavy load of transaction requests (even hundreds of thousands of requests per hour) that arrive from several offices simultaneously.

and they could already communicate with other Lappeenranta University of Technology and Telecom Finland

Tutorial on Intelligent Networks

The batch functions are for example realizations of the

points. Furthermore, the long development time frames

money transfer requests such as payment of salaries every

and the then-available technologies favored producing

month ar any account transfers. These computer systems

this new service by slightly rearranging the internal

need to serve the realtime queries and give responses to

structure of the switching systems and “squeezing in” the

thousands of locations worldwide.

new capability. The end result was that DDD increased considerable network-related data in the local switches

2.2

and also added new functions related to the network

Switching systems development

connection capabilities into the local switches. On many From 1870’s to 1950’s, the primary focus of swithing

of the existing switches, this involved adding specialized

system

better

“boxes” to correctly interpret the new dialed numbers and

technologies for permitting two people to engage in voice

route them to the correct places for proper DDD

communications over larger and larger distances and to

connectivity.

development

was

producing

make this technology more readily available, cheaper, and more reliable. During this period the industry moved from local calls being handled by operators with plug boards, to step-by-step switches, to panel switches, to crossbar switches and to Stored Program Controlled (SPC) switches. It is interesting to remember that in 1925 one of the most significant breakthroughs was the separation of the connection control activities from the maintenance of the actual connections during an active call.

This change, over time, allowed the switching

systems to reuse the more complex resources of the switch (those used for initiating and setting up a call), thus ending an era of having to duplicate these costly resources and having them tied up for the entire duration of a call. One of the major implications of switching systems development during this period was that almost all the information about how connections were to be created resided on the individual switches, specifically, subscriber data, information about how to provide the limited functions available at that time, and implicit network information were all contained in each switch

To get some idea of the development of technology associated with the interconnection aspects of the telecommunications at that time, we can look at one of the services we consider basic today. In 1956, the first undersea cable using repeaters was activated at a cost of about $6 million/circuit resulting in a cost of about $75/minute. By 1976, the cost per circuit was reduced by a hundredfold, thus permitting later developments to focus more on providing various services beyond connection. One of the driving forces for more complex services at this time was the reduction in the cost of the basic connections so that groups of customers with specialized needs came to the market asking for capabilities beyond simple connectivity. This was the beginning of the transition period in which the structure of the telecommunications industry was changing away from the former connection focus toward a new service focus. However, the pace of change was slow given the technological problems that still had to be overcome to provide fast and economical connections with high quality. Thus, there was no driving need to reorganize

Benne93.

the basic structure of what existed; nor was there any real In the 1950’s, Direct Distance Dialing (DDD) began to be

guidance as to what kinds of services the customers

deployed as a new service, but this was still a

would be willing to purchase as a service marketing was

continuation

in its infancy Benne93.

the

general

focus

provide

telecommunications connections between two fixed Lappeenranta University of Technology and Telecom Finland

Tutorial on Intelligent Networks

During the 1960’s and 1970’s, the requests for additional

a large expansion of the types of information being placed

services began to grow, but the pace was rather slow by

on the switches, e.g., variations of call models, more

today’s standards since the technology to support these

network-related information was brought into the

new services was not readily available on the general

switches, and data under the control of the end users was

market. Since the new SPC-exhanges were able to swith

moved onto the switches (speed calling lists, centrex data,

64 kbps connections transmitted over digital PDH

etc.). As this data was moved onto the switches, the

systems, it was a natural idea to propose this capability as

programs to manipulate the data and ensure its integrity

a basis for data communications. This was the birth of

also had to be installed in the switches. This resulted in

the ISDN-concept (Integrated Services Digital Network)

the switches becoming also very general data control and

where two digital 64 kbps data channels and one digital

usage systems Benne93.

16 kbps signalling channel was provided to the customers. ISDN was an important concept since the current service-driven thinking was created during its development. For example, the other 64 kbps channel could be used for speech and the other for data transmission simultaneously. The whole capacity of 128 kbps could also be used for a reasonably high quality compressed real time video connections. The availability of ISDN growed, however, much slower than was expected. The reasons for this were the existing large installation base of analogous switching and transmission systems incapable to support digital channels.

Once

again, it was more economical and easier to “squeeze” the new capabilities into the existing switching systems than to change the switches and have to replace the embedded base with newer technologies.

This slow evolution

process was aided by the small market base for the newer

As we entered the 1980’s, the advanced computer technology started to penetrate from industrial and office use also to low end products.

Computer technology

became as an embedded technology in customer equipments such as faxes and portable phones, and as a control technology for the management and intelligent control

networks.

The

computer

technology

breakthrough was facilitated by the introduction of open computer platforms (UNIX and Personal Computers, PCs), the fast reduction of cost in computing and the networking of PCs, minicomputers and mainframes. The PCs provided a general platform for digital customer premises equipments, capable to communicate via Local Area Networks and Public Networks. This, in conjunction with the lowering of transmission and interconnection service costs, resulted in an exponential growth in the demand for newer and more flexible telecommunications

services.

services. Another major factor driving toward more For example, the office automation technologies available

specialized

services

was

the

liberalization

and

were not very advanced and did not produce digital data

competition in telecommunications business.

storage and transfer. Also, the derivative technologies

United States the operator competition started with the

associated with the growth of computers, personal

breakup of the Bell System and resulting competition,

computers, and microchip technology had not reached a

where services were the factor that differentiated one

state where they were demanding telecommunication

carrier form another. Furthermore, with diversiture, the

services much beyond classical interconnectivity services.

former local operating companies were permitted to make

In the

instructions into one anothers’ traditional service areas During this period, the efforts to put more and more new service capabilities onto the switching systems resulted in

and, to do this effectively, they needed to have something to offer that was not available from the local service

Lappeenranta University of Technology and Telecom Finland

Tutorial on Intelligent Networks

provider. All of these changes resulted in customers being

UMTS GSM

more aware of what technology provided and demanding that the telecommunications industry should

meet the

Corporation networks

new requirements for services Benne93. The

1990’s

and

beyond

will

demand

that

the

telecommunications industry change its basic ideas about the structure of their networks and how they will evolve. Up until the 1980’s, network development was driven by

MBS

NMT

Packet data networks Analogous telephony service

Modem services

B-ISDN

Broadband IN

IN MEDIA

ATM

ISDN SS7

Batch 'Real' processors computers

the need to provide cheap and efficient interconnections between two fixed points.

There was only minor

1950

1960

1970

1980

1990

2000 Time

emphasis on structuring the switching systems to be readily adaptable to the rapidly changing service requirements that have appeared in the last decade. Now that cheap, efficient interconnection capabilities are available, the relative roles of the interconnection capabilities and end-user services will be interchanged. The demand for more and more customer based services will continue to grow, and there will be an inceasing demand for having the new services in shorter and shorter time frames. Thus, the basic structure for the network, and especially the structure and function of the switching systems, will change to accomodate this need for rapid deployment of more and more custom oriented services. In summary, the telecomunications industry, which has been interconnection-driven, will, in the future, be service-driven.

In this tutorial we shall discuss these

modern trends more thoroughly..

Figure -2. The development of telecommunications. First, the beginning of data transfer by the use of analogous telephony service was an important stage in the history. This service was not good for use in corporations because of its low data transfer speed. Then, there was a need for a data transfer service that used billing by data amount while the expences of the analogous telephony service consisted mainly of the data transfer time. The packet switched data networks were developed especially for corporations use. Second, CCITT (Consultative Committee for International Telephone and Telegraphy) introduced its seven layer OSI protocol stack SS7 to replace the analogous signalling system. This was the corner-stone

for

the

digital

telecommunications

technology that is used, for instance, in ISDN (Integrated Services Digital Network). In the late 1980’s radio signalling technology was advanced enough to provide

2.3

Turning-points in telecommunications

digital telephony service. The GSM (Global System for Mobile communications) mobile phone technology,

Several turning-points can be found in the history of telecommunications technology (marked as circles in the figure 2) .

introduced ito use n 1991, is also suitable for low-speed data transfer. The Intelligent Network is an architecture capable to integrate all the telecommunications services mentioned in a flexible way. The

telecommunications

networks

and

wide

area

networks used PDH (Plesiochronous Digital Hierarchy) technology in the physical data transfer. At the Lappeenranta University of Technology and Telecom Finland

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introduction of CCITT’s SDH (Synchronous Digital Hierarchy) technology the physical data transfer rates increased

remarkably.

new

technology,

ATM

(Asynchronous Transfer Mode), was introduced to use the available bandwidth efficiently in the 1992. By the introduction of ATM it was possible to imagine of such concepts as B-ISDN (Broadband Integrated Services Digital Network ), broadband mobility and broadband IN. These technologies will be discussed more accurately later on. Broadband infrastructure will make it possible to introduce advanced value added, mobile and media services (Figure 2-3).

Figure 2-4. Evolution of mobile services and systems. In the next five years the third generation mobile networks will be developed called the UMTS (Universal Figure 2-3. Turnover Value of Service Types

Mobile Telecommunications System).

UMTS was

researched in the RACE program of EC (European 2.3.1

Community) and ETSI’s group SGM5, which research

UMTS

UMTS (Universal Mobile Telecommunications System ) is intended to be an international standard for global telecommunication system. It is a third generation mobile telecommunications system which integrates several second

generation

mobile

systems

cordless

telephones (CT2 (Cordless Telephone 2) and DECT (Digital

European

Cordless

Telecommunications)),

mobile telecommunications systems (GSM and PCN) and

will be continued in the ACTS program of EC. This new generation is based on application and service oriented technology

that

supports

on-demand

transmission

capacity up to 2 Mbps in various radio environments. The ultimate goal is to provide seamless end-to-end services to the user by using a combination of fixed and wireless/mobile access tecnologies, where a mobile phone could be used at home, office and elsewhere.

radio message systems (ERMES (European Radio

UMTS is an open system which is based on TMN and IN

Message System)) Hara93 (Figure 2-4).

concepts. The system supports ISDN services and could be at some degree compatible with B-ISDN with ATMswitching and possible broadband mobile access. This system is a very advanced telecommunications system that supports global mobility and Intelligent Network

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services and is not expected to be introduced before the

technology is also maturing and will provide a cost

year 2000.

effective platform for service provision.

When the

broadband customer access will be available, interactive There has also been proposals for still higher speed mobile networks such as MBS (Mobile Broadband System), which could support bit rates up to 34 Mbps. However, the architectures of these proposed networks are still open, and they will depend heavily on how the

business and consumer services based on video and multimedia will become possible. Common to all these developments will be the computer controlled structure of modern telecommunications, where protocols, application technology and resource management are key factors.

control of mobility and intelligence will be distributed over the network.

2.3.2

MEDIA

With media concept we understand here both radio, television and cinema, and press and publishing industries. All these will be available in electronic digital forms either as stored media or interactively from the distribution network. In modern telecommunications the emerging competitive media services market and the new technological breakthroughs will bring remarkable changes. market

changes

are

due

the

The

integration

telecommunications and information technology, which brings interactive real time video and multimedia services available to users. Examples of these services are digital interactive TV, video on demand services for banking, shopping and leasure, electronic press and publishing. The technological requirements for these services are cost effective

broadband

transmission

and

access

technologies, flexible computer based management and control of services and networks, switching and service applications and the support of mobility. In technology substantial new breakthroughs are going on.

The introduction of cellular radio networks and

mobility is probably the most influential one in the next few years. The broadband transmission and switching

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Reference Model (OSIRM) in 1980. SS7 is fully digital

3. Computer Telecommunications

Controlled

and SS7 protocol stack corresponds to the seven layers of the OSIRM and includes the Application Services and User Parts (UP) (Figure ).

The signalling network

structure component of SS7 is the Network Service Part 3.1

(NSP), and it consists of the Message Transfer Part

CCITT Signalling System No. 7

(MTP) and the Signalling Connection Control Part The word ‘signalling’ ment the transfer of analogous

(SCCP).

The OSIRM layers 4 - 6 are provided by

signals in a network, for example in the analogous

Intermediate Service Part (ISP) and each User Part.

telephony network the activation of nonintelligent switches, just a few decades ago. In the context of modern telecommunications, signalling can be defined as the system that enables Stored Program Control exchanges, network databases, and other “intelligent” nodes of the network to exchange messages related to call setup, supervision, teardown (call/connection control information) distributed

Modar90, application

information

needed

for

processing

(inter-process

query/response, or user-to-user data) and network

SS7 is quite an advanced protocol stack. It includes capabilities for congestion control and overload control. It also includes features for avoiding congestion by alternative routing or capacity expansion when heavy load is detected. With congestion is ment generally, shortage of resources, which is caused by an excessive amount of load, or a failure that reduces the installed capacity of a network element. SS7 also includes capabilities

for

sending

congestion

and

overload

indications to the adjacent exchanges or traffic sources.

management information.

M3010 Just a few decades ago (and even today), the telecommunications networks used analogous signalling, based on frequency tones, between network nodes. Some key attributes of these signalling methods are that they are

OSI Reference Model

SS7 protocol stack OMAP

ASEs

Application TCAP UP

Presentation

inband (i.e. signalling information is conveyed over the

Session

same channel that is used for speech) Modar90; call set-

Transport

up times are long (from about 10 to 20 s); limited

ISP

SCCP Network MTP Level 3

information can be transferred resulting, among other things, in restrictive network routing capabilities.

Data link

MTP Level 2

Physical

MTP Level 1

With the introduction of electronic processors in Figure -1. SS7 protocol architecture.

switching systems came the possibility of providing Common Channel Signalling (CCS). This is an out-ofband signalling method in which a common data channel

3.1.1

is used to convey signalling information related to a

MTP consists of levels 1-3 of the SS7 protocol stack and

number of trunks. Modar90 CCITT published this new

it provides a connectionless message transfer system that

signalling protocol stack SS7 (Signalling System No. 7)

enables signalling information to be transferred across the

based on CCITT OSI (Open Systems Interconnection)

network to its desired destination. Functions are included

Network Services Part

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in MTP that allow system failures to occur in the network

3.1.2

without adversely affecting the transfer of signalling

The User Part forms the most upper layer of the SS7

information. So the overall purpose of MTP is to provide

protocol stack that use the services provided by the lower

a reliable transfer and delivery of signalling information

layers SCCP and MTP. User Part functions are ISDN-UP,

across the signalling network and to have the ability to

TCAP (Transaction Capabilities Application Part) and

react and take necessary actions in response to system and

OMAP (Operations, Maintenance, and Administration

network failures to ensure that reliable transfer is

Part). The ISDN-UP is not discussed in this paper. TCAP

maintained. The first level of MTP presents the signalling

refers to the set of protocols and functions used by a set

data link functions. A signalling data link functon is a

of widely distributed applications in a network to

bidirectional transmission path for signalling, consisting

communicate with each other. TCAP directly uses the

of two data channel operating together in opposite

service of SCCP. Essentially, TCAP provides a set of

directions at the same data rate. It fully complies with the

tools in a connectionless environment that can be used by

OSI’s definition of the physical layer. Level 2 of MTP

an application at a node to invoke execution of a

presents the signalling link functions. The signalling link

procedure at another node and exchange the results of

functions correspond to the OSI’s data link layer.

such invocation. As such, it includes protocols and

Together with a signalling data link, the signalling link

services to perform remote operations. It is closely related

functions provide a signalling link for the reliable transfer

to the OSI Remote Operations Service Element (ROSE).

of signalling messages between two directly connected

The OMAP of the SS7 protocol stack provides the

signalling points. The third level of MTP presents the

applications protocols and procedures to monitor,

signalling network functions. They correspond to the

coordinate, and control all the network resource that make

lower half of the OSI’s network layer, and they provide

communications based on SS7 possible. Modar90

User Part

the functions and procedures for the transfer of messages between signalling points, which are the nodes of the signalling network. Modar90

3.1.3

Signalling network structure

SCCP provides additional functions to MTP for both connectionless and connection-oriented network services. SCCP enhances the services of the MTP to provide the functional equivalent of OSI’s network layer. The addressing capability of MTP is limited to delivering a message to a node and using a four-bit service indicator to

distribute

messages

within

the

node.

SCCP

supplements this capability by providing an addressing capability that uses DPCs (Destination Point Code) plus Subsystem Numbers (SSN). The SSN is local addressing

Figure -2. CCITT SS7 network structure.

information used by SCCP to identify each of the SCCP

Signalling networks consist of signalling points and

users at a node. Modar90

signalling links connecting the signalling points together. (Figure ) As alluded to earlier, a signalling point that transfers messages from one signalling link to another at

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level 3 is said to be a STP (Signalling Transfer Point).

purposes: several network and devices, digital and

Signalling points that are STP’s can also provide

analogic transmission systems, circuit- and packet

functions higher than level 3, such as SCCP and other

switched data networks, public exchanges and PABX’s

level 4 functions like ISDN-UP. When signalling point

(Private Access Branch Exchange).

has an STP capability and also provides level 4 functions like ISDN-UP, it is commonly said to have an integrated STP functionality. When the signalling point provides only STP capability, or STP and SCCP capabilities, it is commonly called a stand-alone STP. Signalling links,

TMN is intended to support different management based areas. These five functional areas are: Performance management

STP’s (stand-alone and integrated), and signalling points

fault management

with level 4 protocol functionality can be combined in

configuration management

many different ways to form a signalling network. The SS7 Network Services Part protocol is specified independent of the underlying signalling network

accounting management security management

structure. However, to meet the stringent availability requirements given below (e.g., signalling route set unavailability is not exceeded ten minutes per year), it is clear

that

any

network

structure

must

provide

The functionality of TMN consists of the following subjects: Error! Reference source not found.

redundancies for the signalling links, which have

the ability to exchange management information

unavailabilities measured in many hours per year. In most

across the boundary between the telecommunications

cases the STP’s must also have backups. Modar90

environment and the TMN environment. the ability to convert management information from

The worldwide signalling network is intended to be

one

structured into two functionally independent levels: the

information flowing within the TMN environment

national and international levels. This allows numbering

has a consistent nature

plans network management of the international and the

the ability to transfer management information

different national network to be independent of one

between locations within the TMN environment

another. A signalling point can be a national signalling

the ability to analyse and react appropriately to

point, an international signalling point, or both. If it

management information

serves both, it is identified by a specific signalling point

the ability to manipulate management information

code in each of the signalling networks. Modar90

into a form which is useful and/or meaningful to the

format

another

that

management

management information user 3.2

Telecommunications Management Network

the ability to deliver management information to the management information user and to present it with

Telecommunications Management Network (TMN) is a

the appropriate representation

generic, management-oriented architecture, intended to be

the abilty to ensure secure access to management

used for all kinds of management services. Appel93 It

information by authorized management information

has been defined in the CCITT M.3000 series standards.

users

According to the concept it intends to meet several Lappeenranta University of Technology and Telecom Finland

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contiguous layers or between the OSF and the NEF; the In TMN architecture there are mainly three architectural points of view each of which can be taken into account when TMN network is designed. These aspects are:

F-type reference point is between the WSF and the OSF; and the X-type reference points are between OSFs belonging to different domains.

fucntional, informational and physical architectures. Each of them studies the network architecture from different apects. 3.2.1

Functional architecture

The TMN functional architecture is described with functional blocks such as the Network Element Function (NEF), The Operations Systems Function (OSF) and Work Station Function (WSF). (Figure ) NEFs model all entities that form the network to be managed. NEFs are to be located physically on network elements. OSF provide the TMN functions for processing, storage and retrieval of management information. They form the core part of the TMN. Four different OSFs can be identified according to a hierarchial partitioning into four layers: the network element management layer, responsible for the

Figure -3. TMN Operations Systems functional hierarchy. Appel93

management of a subset of the network elements in the whole

network;

the

network

management

layer,

responsible for the technical provision of services requested by the upper layer. This layer has an overall view of the network. The service management layer is responsible for all negotiations and resulting agreements between a customer and the service offered to this customer. The business management layer is responsible for the total enterprise. Therefore, it is possible to identify different types of OSFs; the NE-OSF, N-OSF, the S-OSF and the B-OSF. WSF represent the functionalities and information modelling entities related to the TMN manmachine communications between the management system and the human operator. Appel93

3.2.2

Informational architecture

TMN informational architecture is based on ObjectOriented (O-O) point of view. Management systems exchange information modelled in terms of managed objects. Managed objects are conceptual views of the resources that are being managed or may exist to support certain management functions (e.g. event forwarding or event logging). Thus, a managed object is the abstraction of such a resource that represents its properties as seen by (and for the purposes of) management. A managed object may also represent a relationship between resources or a combination of resources (e.g. a network). Error! Reference source not found.

Between the function blocks NEFs, OSFs and WSFs there are different kind of reference points: Q-, F- and Xtype. The Q-type reference point is between OSFs of

Management of a telecommunications environment is an information

processing

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application.

Because

the

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environment being manages is distributed, network

and they are specified more entirely with the lower layer

management is a disributed application. This involves the

attributes.

exchange

management

information

between

management processes for the purpose of monitoring and controlling the various physical and logical networking resources (switching and trasmission resources). Error! Reference source not found. The TMN architecture is based on Manager/Agent architecture. (Figure ) A manager takes care of the distributed applications part that issues management operation directives and receives notifications. The agent role if the part of the application process that manages the associated managed objects. The role of the agent will be to respond to the directives issued by a manager. It will

Figure -5. Management Information Tree.

also reflect to the manager a view of these objects and emit notifications reflecting the behaviour of these objects.

3.2.3

Physical architecture

NEFs identify all the network elements as physical entities in TMN. Operations Systems (OS) form the core part of every TMN domain. The TMN physical architecture is not discussed more accurately in this paper.

Figure -4. Interaction between Manager, Agent and managed objects.

3.3

Intelligent Network

3.3.1

The need for IN

the

past

few

years

the

development

In TMN the manager uses polling method to get the

telecommunications networks has been rapid. The

information from the agents. The agents store the

telecommunications network functions before were

statictics information in their databases that are called

controlled mainly by operators. The desire to share data

MIBs (Management Information Base). A MIB is a

and distribute application processing among network

conceptual database structure. It represents the set of

elements, the need for standard interfaces between them

managed objects within a managed system. The structure

Garra93 and user demands for more sophisticated

of the MIB is often showed in the form of a tree. This tree

telecommunications services has changed the controlling

is called a Management Information Tree ( MIT). (Figure -

of network elements notably. The telecommunications

5) The tree is organized in a hierarchical way. At the

network elements today are controlled by the network

upper parts of the tree resides the most meaning attributes

operator, the service provider or the customer himself.

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To integrate the control and management of different

3.3.2

services inside the operator, or to be able to provide third

Intelligent Network (IN) is an architectural concept for

party control and management services,

the operation and provision of new services which is

control and

Definition of Intelligent Network

management interfaces with software support are needed.

characterized by [Q1201]:

The development of IN architecture was initiated by

extensive use of information processing techniques;

efficient use of network resources;

modularization and reusability of network functions;

integrated service creations and implementation by means of

Bellcore in USA almost ten years ago in order to help the Regional Bell Operating Companies to become more competitive

deregulated

telecommunications

environment. The original goal was to provide network operators with the ability to introduce, control and manage services more effectively by using a centralized

the modularized reusable network functions;

database in a Service Control Point (SCP) for controlling and managing the various network services. Lauta93

flexible allocation of network functions to physical entities;

The objective of IN is to allow the inclusion of additional

portability of network functions among physical entities;

standardized communication between network functions vie

capabilities

facilitate

provisioning

service,

independent of the service or network implementation in

service independent interfaces;

a multi-vendor environment. Service implementation independence allows service providers to define their own

services independent of service specific developments by

service subscriber 1) control of some subscriber-specific service attributes;

equipment vendors [Q1201]. -

Network implementation independence allows network

service user 2) control of some user-specific service attributes;

and service operators to allocate functionality and resources within their networks and to efficiently manage their networks independent of network implementation specific developments by equipment vendors.

standardized management of service logic.

IN is applicable to a wide variety of networks, including but not limited to: public switched telephone network

The network architectures, so far, have developed almost

(PSTN) mobile, packet switched public data network

independently of each other. This point of view, of

(PSPDN) and integrated services digital network (ISDN)

course, causes the network operators and service

- both narrowband-ISDN (N-ISDN) and broadband-ISDN

providers to provide independently implemented service

(B-ISDN).

to customers.

The basic idea of IN has been that it

facilitates the provisioning of services independently from the telecommunications networks and equipment vendors. So, the IN acts as a distributing and centralizing framework of the telecommunications services. With this

IN supports a wide variety of services, including supplementary services, and utilizes existing and future bearer services (e.g. as those defined in N-ISDN and BISDN contexts).

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3.4

USID:

Numbering and Services

User service identifier. A USID uniquely identifies a service

profile on an access

interface.

The user identification has mainly been based on the access points of the telecommunications network. The

TID:

users’ access points were separateded from each other

If two terminals on an interface subscribe to the same service profile,

with the Network ID (N_ID). This N_ID was at the early

then the two terminals will be assigned the same service USID.

telecommunication systems the telephone number that did

However, two different TIDs are required to uniquely

not support any mobility at all.

the two terminals.

The introduction of

Terminal identifier. A TID value is unique within a given USID.

dentify each of

mobile services and third party media services will create new needs for customer and service identification (Figure 3-6). In Figure 3-6 service identifications can contain also other service related data than the service or program

EID: Endpoint identifier. The endpoint identifier information element is used for terminal identification. The endpoint identifier parameters contain a USID and TID and additional information used to interpret them.

identification itself.

In OSI environment there are two naming conventions that can be applied to services, the Object Identifier specified in the ASN.1 notation [ISO 8824] and the Distinguished Name specified in the Directory standard [ISO9594]. Figure 3-6. Numbering Types The ISDN supplementary services identifications consist

The services can be considered as

Application Entity instances, whose names can be presented using either Object Identifiers or Relative Distinguished Names [ISO 7498-3]

of the following identifiers [Q932]: There can be three main identification types depending on Service profile:

Service profile refers to the information that the

the roles in the network: N_ID’s, S_ID’s (Service ID) and

network maintains for a given user to characterize the service offered

U_ID’s (User ID) (Figure 3-7). S_ID defines the service

by the network to that user. As an example, this may contain the

that is used by the user via the network.

association of feature identifiers to specific supplementary services. A

the exact user irrespective of the network. The relation

service profile may be allocated to an access interface or to a particular

between user and network ID’s in old telephone networks

user equipment or a group of user equipments.

is hence U_IDN_ID.

SPID: The service profile identifier is a parameter

carried in a service

U_ID defines

The service identification is

dependent on these three types.

profile identification information element that is sent from the user to

In the future there can exist several other relations too.

network to allow network assignment of a USID and TID. A user's

For example, the mobility of users and services. The user

SPID should uniquely identify a specific profile of service

can move from N_ID to another and use a service that

characteristics stored within the network. The SPID will allow the

could

network to distinguish between different terminals that would otherwise

telecommunications network or serve the user as a mobile

be indistinguishable (e.g., same N_ID). The SPID value is provided to

service. Also from different U_ID’s can be produced

the user at subscription time.

groups where the telecommunications network is used as

either

distributed

throughout

the

a private network inside the whole telecommunications

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system. As a more advanced telecommunications system, GSM uses for mobility the relation where each user with U_ID is attached to a Base Station channel with invisible N_ID. This relation is updated in roaming and handovers that the GSM network manages. The Intelligent Network differentiates the user, network and service from each other. This description can manage mobility from each of its components and even of different Intelligent Networks when IN uses services from other networks.

Figure 3-7 Different relations between identifications.

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Create opportunities for non-RBOC service

Intelligent Network Architecture

vendors to offer services that stimulate network usage

4.1

Overview of IN

As with the past telecommunications technology, it was

The term Intelligent Networks (IN) is used to describe an

not desirable to introduce short term services, because of

architectural concept which is intended to be applicable to

the long implementation and development period. Now,

all telecommunications networks and aims to ease the

with IN technology it is possible to introduce new

introduction and management of new services.

services rapidly without affecting the available services. IN defines a large set of standards that describe the

The objective of IN is to allow the inclusion of additional

interfaces between different network control points. With

capabilities

service,

only specifying the interfaces IN makes it possible for

independent of the service or network implementation in

vendor systems to provide with different products and ,of

a multi-vendor environment. Service implementation

course, for operators to use any of these products in their

independence allows service providers to define their own

network configuration. IN includes also capabilities for

services independent of service specific developments by

other than operators to introduce new services into the

equipment vendors [Q1201].

telecommunications network. This will change the

facilitate

provisioning

Network implementation independence allows network and service operators to allocate functionality and

structure of the telecommunications business, which is the main concern in the section 5 of this paper.

resources within their networks and to efficiently manage

The IN’s main advantage is the ability to control

their networks independent of network implementation

switching and service execution from a small set of

specific developments by equipment vendors.

Intelligent Network nodes known as Service Control Points (SCP). SCPs are connected to the network

4.1.1.

switches (known as Service Switching Points) via a

Origins of IN

The Intelligent Networks is a telecommunications network services control and management architecture. In February 1985, Regional Bell Operating Companies (RBOC) submitted a Request For Information (RFI) for a Feature Node concept with the following objectives Ambro89:

standardized interface; CCITT Signalling System No. 7. The SS7 will facilitate a multi-vendor SCP and SSP marketplace, and the standardization of application interfaces allows a multi-vendor software marketplace for SCP applications (that is, the service control logic and its related data) (Figure -1). The SSPs detect when the SCP should handle a service. The SSP forwards a standardized

Support the rapid introduction of new

SS7 (TCAP) message containing relevant service

services in the network

information. Via the TCAP message, the service control

Help establish equipment and interface

logic in the SCP directs the SSPs to perform the

standards to give the RBOCs the widest

individual functions that collectively constitute the

possible choice of vendor products

service (such as connecting a subscriber number or an announcement machine) Ambro89.

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The IN’s long term goal is the ability to introduce new

IN/1 requires updates in the SSP and SCP in order to

services, or change existing services quickly, without

support a new service. A typical IN/1 service is the

having to adapt SSP software (only parameters or trigger

Green Number Service (GNS) with which a subscriber

updates). The adaptation will be confined to the SCP

can call a number free of charge. The SSPs contain

where parameters or stimuli are updated. This goal was

triggers (such as the value of the dialed digits) that tell

first planned by Bellcore to be achieved in two stages:

the SSP to send a message to an SCP in order to get

IN/1 and IN/2 Ambro89 IN/1 definitions introduced the

information about the destination to which the call

term Intelligent Network in 1986 and in 1987 IN/2

should be routed. Migration from IN/1 to IN/2 implies

definitions were introduced. In 1988 IN/2 was delayed

significant changes in the SSPs to accomodate new

and IN/1+ was introduced instead.

services.

In 1989 Bellcore

abandoned IN/1+ for several reasons, some being problems in the technology and lack of multivendor involvement.

Instead a MultiVendor Initiative (MVI)

was started in 1989 to define Advanced Intelligent Network (AIN).

At the same time CCITT and ETSI

started work on IN. The IN basic concepts for a service dependent architecture were introduced already in IN/1. The AIN concepts were essentially those of IN/2 defining a fully service independent architecture with total separation of service logic from the underlying seitching system. These principles were accepted also by CCITT and ETSI work. The AIN Release 1 and CCITT CS1 were published in 1993. Let us finally summarize early IN/1 and IN/2 outlines.

Stage 1: IN/1 Once IN/2 is in place, no updates need be made to the SSPs software when new services are introduced. The IN/2 triggers advise the SSP whether to complete execution locally. All SSPs and SCPs contain set of basic service elements (for example, connect two lines, disconnect a line). The SCP also contains service relevant data. These basic service elements are knows as Functional Components (FC) from which each service can be contructed. A customer could conceptualize a new service and the network operator, via the SMS/SCP, could construct it quite rapidly. Any successful and widely-used service may be downloaded (via the service logic) to, but transparent to, the SSPs (if this is more economic or provides a desired higher grade of service). This facilitates complete rapid service creation. Rapid service creation and user programmability will take place in the SCP and the SMS. Stage 2: IN/2

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activities were started in 1989's.

The first available

publications were the Advanced Intelligent Network (AIN), and after that CCITT and ETSI provided their first draft recommendations. mainly

based

the

Our presentation here is

CCITT,

presently

ITU-T,

recommendations.

4.1.2.

IN standardization

4.1.2.1 IN standards bodies The IN standards are defined by ETSI and CCITT. Also, in the USA, the work is being done by Bellcore, which is not a standards body but provides the major input to the American National Standards Institute committee TS.1. Roger90

4.1.2.1.1ETSI ETSI was created in 1988 and its members are the European

Telcos

(Telecommunications

Operating

Company), manufacturers, user representatives and research bodies. ETSI has two purposes. IN belongs to the latter category. Roger90 to achieve workable versions of international Figure -1. Intelligent Network overview. Homa92

standards for the European environment

An Intelligent Network is able to separate the

to define European standards in areas where quick

specification, creation, and control of telephony services

response is required for technical development

from physical switching networks. The key benefit of this capability is that exchange carriers will be able to rapidly

4.1.2.1.2CCITT

engineer new revenue-producing services, in response to

Work on international standards for IN began at CCITT

market opportunities, without having to rely on lenghty

in 1989. Study Group XI.4 is responsible of the

cycles for implementing them entirely on switching

standardation. CCITT expects that the specification and

fabric. Ultimately, service creation, or at least service

deployment of IN will continue over a number of study

customization, can be extended to subscribers Homa92.

periods. CCITT name has changed to ITU (International Telecommunications Union) and there the Special Interest

The original IN concepts IN/1 and IN/2 were not

Group (SIG) is T (ITU-T). Its approach to the

considered sufficient

to support vendor independence

development of IN standards assumes that it is necessary

and open interfaces, and extensive standardization

to start with a minimum set of criteria which are

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sufficiently open ended that they can evolve to meet the

Figure -2. Phased standardation of IN.

needs of the long-term concept as this becomes a practical reality. Roger90

4.1.2.3 Structure of CCITT IN standards

Both ETSI and ANSI are keen to ensure that CCITT recommendations agree substantially with their own activities, and collaboration between all three bodies is likely to be an important determinant in the rapid development of realistic IN standards.

The basic standard that defines the framework of other IN standards is Q.1200 - Q-Series Intelligent Network Recommendations Structure. The standards have been numbered so that every new CSx will have a number that begins with 12x and the description of the CSx recommendation

part

will

numbered

also

systematically such as 12xy. (Table -1) So, the principles 4.1.2.2 Phased standardization

introduction for IN CS2 will be recommendation number

To meet the goals and objectives, CCITT has embarked

Q.1221.

on a phased standardation process toward the target IN architecture (INA) [Q1201]. CCITT works on defining a

00 - General 10 - CS1

1 - Principles Introduction

20 - CS2

2 - Service Plane (not included for CS1)

The IN

30 - CS3

3 - Global Functional Plane

subjects of standardization are called Capability Sets

40 - CS4

4 - Distributed Functional Plane

(CS).

50 - CS5

5 - Physical Plane

set of capabilities for each phase and simultaneously on evolving the view of the target IN architecture called the long-term capability set (LTCS) (Figure -2)

The Capability Sets involve service creation, also

network

60 - CS6

6 - For future use

and

network

70 - CS7

7 - For future use

internetworking. These CS’s are backwards-compatible

80 - CS8

8 - Interface Recommendations

90 Vocabulary

management management, the

and

interaction

service

CS’s

and

processing so

the

standardation

and

implementation of the services can be progressed through a sequence of phases Garra93.

9 - Intelligent Network Users Guide

Table -1. IN recommendations structure. 4.1.2.4 Capability Set 1 It has been an international and european wide aim to define the first step of INA. These recommendations are gathered into a set called IN Capability Set 1 (CS1). There are two standardation organisations working on CS1: CCITT and ETSI. CCITT has gathered these recommendations into the Q.121y -series. (Table -2) CCITT’s and ETSI’s standards do not substantially differ from each other. CCITT Study Group XI, Working Party XI/4 includes representatives

from

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most

the

important

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telecommunications network operators and equipment

given CCITT’s objective of evolving IN from existing

vendors in the world. Study Group XVIII also is involved

networks. The latter approach was service-driven and it

in the initial set of IN standards, and is sharing

focused on identifying a set of IN CS1 services and

responsibility for the Introductory Recommendations. At

Service Features. Then driving these down through the

these meetings, there is an obvious willingness to

INCM in order to identify the set of service-independent

strongly focus on achieving a realistic initial set of IN

capabilities for IN CS1, evolvable to the target set of IN

capability, which is both technically implementable and

capabilities, and verify that this set could be supported by

commercially deployable.Duran92

the functional and physical architectures defined via the “bottom-up” approach Garra93.

Recommendation Q.1200

Q-Series Intelligent Network Recommendations Structure

Recommendation Q.1201

Principles of Intelligent Network Architecture

IN CS1 defines capabilities of direct use to both

Recommendation Q.1202

Intelligent Network - Service Plane Architecture

switched voice/data services either defined or in the

Recommendation Q.1203

Intelligent Network - Global Functional Plane Architecture

characteristic of the target set of IN CS1 services is that

Recommendation Q.1204

Intelligent Network - Distributed Functional Plane Architecture

they apply during the setup phase of a call or during the

Recommendation Q.1205

Intelligent Network - Physical Plane Architecture

service

Recommendation Q.1208

Intelligent Network - Application Protocol General Aspects

Recommendation Q.1211

Intelligent Network - Introduction to Intelligent Network Capability Set 1

equipment suppliers will support interworking of IN CS1

Recommendation Q.1213

Intelligent Network - Global Functional Plane for CS1

more complex services such as those that apply during the

Recommendation Q.1214

Intelligent Network - Distributed Functional Plane for CS1

charging, and user interaction capabilities may be used to

Recommendation Q.1215

Intelligent Network - Physical Plane for CS1

Recommendation Q.1218

Intelligent Network - Intelligent Network Interface Specifications

Recommendations Q.1219

Intelligent Network Users guide for Capability Set 1

Table -2. IN CS1 recommendations. In defining IN CS1, CCITT applied the INCM (Intelligent Network Conceptual Model) using both

manufactures and network operators in support of circuitprocess of being defined by CCITT. The primary

release phase of a call. CCITT chose this single-ended characteristic

limit

the

operational,

implementation, and control complexity for IN CS1. Even with this limitation, it may be expected that capabilities with existing switch-based services, including active phase of a call. For example, IN CS1 routing, customize or improve existing switch-based services to better satisfy market needs. Garra93 It is anticipated that CS1 recommendations of CCITT and ETSI will be adopted world-wide. This can help to develop open interfaces between the SSP (Service Switching Point) and SCP (Service Control Point), thus putting into effect one of the important goals of the IN, namely vendor independence. Lauta93

“bottom-up” and “top-down” approaches. The former approach focused on modelling the capabilities of

4.1.2.5 IN CS1 Services

existing networks in terms of functional and physical

Allthough, by nature, the IN is a service independent

architectures that could evolve the target IN architecture,

architecture, it is relevant to describe the general CS-1

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Automatic Alternative Billing (ABB)

Mass Calling (MAS)

Abbreviated Dialling (ABD)

Malicious Call Identification (MCI)

Account Card Calling (ACC)

Premium Rate (PRM)

Credit Card Calling (CCC)

Security Screening (SEC)

Call Distribution (CD)

Selective Call Forward on Busy/Don’t Answer (SCF)

Service Features, and can be optionally enhanced by other

Call Forwarding (CF)

Split Charging (SPL)

Service Features. A Service Feature is a specific aspect of

* Completion of Call to Busy Subsrciber (CCBS)

Televoting (VOT)

* Conference Calling (CON)

Terminating Call Screening (TCS)

Call Rerouting Distribution (CRD)

User-Defined Routing (UDR)

Destination Call Routing (DCR)

Universal Access Number (UAN)

Follow-Me-Diversion (FMD)

Universal Personal Telecommunications (UPT)

Freephone (FPH)

Virtual Private Network (VPN)

service capabilities. The services and Service Features that are to be supported by CS-1 are fundamental to the CS-1 Service Building Blocks, call processing model and service control principles. The target set of CS-1 defines several services (Table -3) and service features. A service is a stand-alone commercial offering, characterized by one or more core

a service that can also be used in conjunction with other services/Service Features as part of a commercial offering. It is either a core part of a service or an optional part offered as an enhancement to a service. Q1201 The service composition and Service Features will be discussed more precisely later on.

Note: The service indicated with a * may only be partially supported in CS1, because they require capabilities beyond those of type A services. Table -3. Target set of IN CS1 services.

4.2

IN Functional Requirements

IN functional requirements arise as a result of the need to provide network capabilities for both customer needs (service requirements) and network operator needs (network requirements) [Q1201]. A service user is an entity external to the network that users its services. A service is that which is offered by an administration to its customers in order to satisfy a telecommunications requirement. Part of the service used

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by customers may be provided/managed by other

Network interworking: A process through

customers of the network. These are often called as third

which several networks (IN to IN or IN to non-IN)

party services and their providers as 3rd party service

cooperate to provide a service.

providers. Service requirements will assist in identifying specific

4.2.1

Service Requirements

services that are offered to the customer. These service

The goal of work for IN is to define a new architectural

capabilities are also referred to as (telecommunication)

concept that meets the needs of telecommunication

services: Network requirements span the ability to create,

service providers to rapidly, cost effectively, and vendor-

deploy, operate and maintain network capabilities to

independently satisfy their existing and potential market

provide services.

needs for services, and to improve the quality and reduce the cost of network service operations and management

Service and network requirements can be identified for

Garra93.

the following areas of service/network capabilities:

requirements are given when defining the IN architecture:

service

creation,

management,

service

management,

processing

and

network network

Service

creation:

activity

whereby

specification phase, development phase and verification phase. Service management: An activity to support the

proper operation of a service and the administration of information relating to the user/customer and/or the

processes:

provisioning,

service

development,

service

control,

billing

service

and

monitoring.

it should be possible to invoke a service on a call-by-call basis

or for a period of time, in the latter case the

service

may

be deactivated at the end of the period;

it should be possible to perform some access control to a service;

network operator, Service management can support the following

it should be possible to access services that span multiple networks;

supplementary services are brought into being through

it should be possible to access services by the usual user network interface (e.g. POTS, ISDN);

interworking. -

In [Q1201] the following overall service

it should be easy to define and introduce services;

it should be possible to support services involving calls between two or more parties;

Network management: An activity to support

the proper operation of an IN-structured network.

it should be possible to record service usage in the network (service supervision, tests, performance information,

Service processing consists of basic call and

charging);

supplementary service processing which are the serial and/or parallel executions of network functions in a

functions in several networks;

coordinated way, such that basic and supplementary services are provided to the customers.

it should be possible to provide services that imply the use of

it should be possible to control the interactions between different invocations of the same service.

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Service requirements for service creation refer to the

providers to define their own services, independent of

network capabilities that are used by network operators

service-specific developments by equipment suppliers.

for the provision of service creation services to CS1 is intended to address services with high commercial

customers.

value, focusing at addressing flexible routing, charging, Service requirements for service management refer to the

and user interaction services. The list of benchmark

network capabilities that are necessary for the provision

services

of service management services to customers.

Standardization of these services, however, is not

and

features

will

listed

later

on.

CCITT’s role. An important characteristic is that the Service requirements for service processing refer to the network capabilities that are necessary for the provision, from a customer's point of view, of basic and supplementary services by an IN-structured network [Q1201].

services

will

technologically

feasible

and

understandable, but do not significantly impact existing deployed technology. In this context, services have been categorized by CCITT as follows: Duran92

The IN is primarily a network concept that

aims for efficient creation, deploynent and management

All type A services are invoked on behalf of and

of supplementary services that enhance basic services.

directly affect a single user. Most type A services

Hence, from a customers point of view the provision of

can be invoked only during call setup of tear down

services is transparent, the customer is unaware whether

and fall in the category of “single-user, single-

the service is provided in an IN way. Service processing

ended (no requirements for representing end-to-end

requirements can be identified for service and access

messaging or control), single point-of-control (no

capabilities. The service capabilities of IN can be applied

requirement fro representing interaction points

to the support of supplementary services for the following

between multiple service logic programs), and

basic services [Q1201]:

single-bearer capability (one media profile)”. Type

bearer services including speech, audio and data

teleservices as telephony, telefax and videotex

broadband interactive services

broadband distribution services

A services may be used in conjunction with other services, switch-based or not, of any type, to form a more complete service package.

Type B services can be invoked at any point during the call. These services may be invoked on behalf

The access capabilities of IN should be applicable to all

of and directly impact one or more users. Feature

telecommunications networks, such as Public Switched

interaction

telecommunications

including

manipulation are capabilities that need to be

Integrated Services Digital Networks (ISDN), both

addressed to deploy these services. Note that it is

narrowband and broadband, packet-switched public data

possible to use type A capabilities to enhance some

networks, and mobile networks. Allthough, IN CS1

existing type B services.

Networks

(PSTN),

and

arbitration,

and

topology

enables only the use of PSTN, PLMN (Public Land Mobile Network) and ISDN, IN should enable service

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The services addressed by CS1 fall under type A services.

Network requirements for service creation refer to the

The type A category lead to a series of advantages in the

network capabilities that are necessary from a network

context of CS1 standardization. First, they represent a

operator point of view for the creation of new

wide range of services of proven value. Second, these

supplementary services.

services depend on well-understood control relationships

consists of specification, development and verification

between network components and this represents an

steps.

The service creation process

achievable target within required time frame of IN CS1 product deployment in 1993. Finally, complexity in the transition to rapid service delivery process is minimized both for service provider and for the equipment

Network requirements for service management refer to the network capabilities that are necessary from a network operator point of view to support the proper operation of services

manufacturer Duran92.

Network requirements for service processing refer to the 4.2.2.

Network Requirements

network capabilities that are necessary for the provision,

Overall network requirements of IN are stated in [Q1201]

from a network operator point of view, of basic and

as follows:

supplementary services by an IN-structured network [Q1201].

it should be possible to move cost-effectively from existing

processing stem from the inability of network operators

network bases to target network bases in a practical and

of traditional "non-IN" networks to rapidly create and

flexible manner

deploy new supplementary services. To overcome this

it should be possible to reduce redundancies among network functions in physical entities

inability the IN aims for: -

rapid service implementations by means of reusable network functions;

it should be possible to allow for the flexible allocationn of etwork functions to physical entities

modularization of network functions;

there is a need for communication protocols that allow

standardized communication between network

flexibility in the allocation of functions

The main network requirements for service

functions via service independent interfaces.

it should be possible to create new services from network

To achieve the goal of fast service implementation, the IN

functions in a cost and time efficient manner

Service Processing Model is introduced (Figure 4-3), and

it should be possible to quarantee the integrity of the

will be studied here in some detail.

etwork when new service is being introduced

it should be possible to manage network elements and network resources such that quality of service and network performance can be quaranteed

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Figure 4-3. IN Service Processing Model. The three main elements of this model are: the basic call processes, the "hooks" that allow the basic call processes to interact with IN service logic, and IN service logic that can be "programmed" to implement new supplementary services. For these elements the main principles are described below: -

Thus, by changing logic at the service control point and modifying network data, a new service that uses existing network capabilities can readily be implemented. In addition In service logic can decide to terminate an interaction session with the basic call process. The basic call process will then resume its execution as specified by the IN service logic. In order to allow fast service

The basic call process should be available all

over the network and is designed to support, with optimal performance, services that do not require special features. In order to achieve flexibility in service processing, the basic call process needs to be modularized into serviceindependent sub-processes such that these can be

implementation, the IN service logic should have a logical view of the network resources that constitute the basic call process and additional (specialised) network functions. For proper service processing, the following principles apply: -

executed autonomously (without interference from the

it should be possible to distribute resources between services in a well balanced way;

outside during execution). -

"Hooks" are to be added to the basic call process

it should be possible for IN supported services to share resources with non-IN supported

forming the links between the individual basic call sub-

services;

processes and the service logic. The "hooks" are able to start an interaction session with the IN service logic. For

it should be possible to provide a different

this it should continuously check the basic call process

method of resource data management from the

for the occurrence of conditions on which an interaction

current embedded method;

session with IN service logic should be started. During an interaction session the basic call process can be

services specific resources.

temporarily suspended. -

it should be possible to introduce IN supported

IN service logic uses a programmable software

environment that needs to be developed to allow fast implementation of new supplementary services. New supplementary services can be created by means of "programs" containing IN service logic. The IN service logic is able, via the "hooks" functionality, to interact with the basic call process. In this way IN service logic can control the sub-processes in the basic call process and the sequencing of these sub-processes.

To define an IN architecture including the network elements within this architecture, there is a need for a call model that describes the real-time behaviour of call control capabilities for the provision of basic and supplementary services. In order to be consistent with the principles of the above-described IN service processing model, the IN call model should cover the following aspects: -

it should specify which basic services can be supported by the model;

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it should model the basic call processes (each

service implementation independence

individual basic service may require its own IN

basic call process);

network implementation independence

it should describe trigger mechanisms

vendor and technology independence

("hooks") that allow the IN basic call process to interact with service logic; -

it should provide a logical view (from the service logic point of view) of call processing functions and network resources, which as a consequence allows fast service implementation;

Each INCM plane represents a different abstract view of the capabilities provided by an IN-structured network. These views address service aspects, global functionality, distributes functionality and physical aspects of an IN ( Figure ).

it should specify the mechanisms according to which an IN-basic call process may interact with the service logic (e.g. single-ended interactions, simultaneous interactions, servicelogic initiated interactions, etc.);

it should be evolvable from the existing technology base.

The CS1 Call Model is presented in detail later in chapter 4.3.2.1.4 of this tutorial. [Q1204]

4.3

IN Conceptual Model

The IN Conceptual Model (INCM) is defined in the CCITT Recommendation Q.1201. The conceptual model is divided into four planes and it forms the basis for the standardation work.

The IN conceptual Model was

designed to serve as a modelling tool for the Intelligent Network. It is also a tool that can be used to design the IN architecture to meet the following main objectives Q1201:

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view is a global (network-wide) basic call processing (BCP) SIB, the service independent building blocks (SIBs), and point of initiation (POI) and point of return (POR) between the BCP and a chain of SIBs. These are described in detail in chapter 4.3.3.1. The Distributed Functional Plane (DFP) models a distributed view of an IN-structured network. Each functional entity (FE) may perform a variety of functional entire actions (FEAs). Any given FEA may be performed within different functional entities. However, a given FEA may not be distributed across functional entities. Within each functional entity, various FEAs may be performed by one or more elementary functions. The manner in which elementary functions result in FEAs is for further study. Service-independent building blocks (SIBs) are realised in the distributed functional plane (DFP) by a sequence of particular FESs performed in the functional entities. Some of these FEAs result in information flows between functional entities.

The information flows consist of

messages which exhance information between functional entities.

The messages comply with OSI structures and

principles (see chapters 4.3.1.2 and 4.4.3). Figure 4-4 IN Conceptual Model Error! Reference

The Physical Plane models the physical aspects of IN-

source not found.

structured networks. The model identifies the different

The Service Plane represents an exclusively service-

physical entities and protocols that may exist in real IN-

oriented view. This view contains no information

structured networks. It also indicates which functional

whatsoever regarding the implementation of the services

entities are implemented in which physical entities.

in the network, e.g. an "IN-type" implementation is not visible. All that is perceived is the network's servicerelated behaviour as seen, for example, by a service user. Services are composed of one or more Service Features (SFs), which are the "lowest level" of services. The Global Functional Plane (GFP) models an INstructured network as a single entity. Contained in this

The entities contained in adjacent planes of the INCM are related to each other. The nature of the relationship is as follows (Q1201): -

Service plane to GF plane: Service features

within the service plane are realised in the GF plane by a combination of global service logic and SIBs including

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the basic call process SIBs. This mapping is related to the

vendors must be able to develop Physical Entities based

service creation process.

on the mapping of Functional Entities and the standard interfaces. Q1201

GF plane to distributed functional (DF) plane:

Each SIB identified in the GF plane must be present in at least one FE in the DF plane. A SIB may be realised in more than one FE. Thus, cooperation of several FEs may be needed. The service logic in the GF plane maps onto one or more DSLs in the DF plane. This mapping is related to the service creation process. -

DF plane to physical plane: FEs identified in the

DF plane determine the behaviour of the physical entities (PEs) onto which they are m mapped. Each FE must be mapped onto one physical entity, but, each PE contains one or more FEs. Relationships between FEs, identified in the DF plane, are specified as protocols in the physical plane. DSLs may be dynamically loaded into physical entities and this mapping is related to the service management process. Let us consider the structures of the INCM planes more thoroughly starting from the physical plane.

4.3.1

Physical Plane

The physical plane is the lowest layer in the IN architecture. It takes action of how the network itself is implemented. It describes the physical architecture alternatives for an IN-structured network in terms of potential physical systems, referred to as physical entities (PE), in a network, and interfaces between these Physical Entities (Figure 4-5). One or more Functional Entities from the Distributed Functonal Plane may be realized in a

Figure 4-5. IN Physical Plane Architecture. 4.3.1.1 Physical Entities

Physical Entity on the physical plane, and one or more

The CCITT recommendation Q.1215 defines the Physical

relationships from the Distributed Functional Plane may

Entities (PE) used by IN. It also describes the interfaces

map into an interface on the physical plane. The physical

between PEs and which IN functionalities are included

plane architecture describes how functional architecture

into them from the Distributed Functional Plane and

map into Physical Entities and interfaces Garra93. Also

which of them are just optional entities.

the requirement for physical plane architecture is that

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4.3.1.1.1SSP

ubiquitous deployment of IN services. This NAP cannot

SSP ( Service Switching Point) is a Physical Entity in the

communicate with an SCF, but it has the ability to

Intelligent

determine when IN processing is required. It must send

Network

that

provides

the

switching

functionality. To make IN capabilities available to all

calls requiring IN processing to an SSP. Q1201

types of access arrangements, we must develop service management independently of the access arrangements. This separation of service management from network access would allow the same network-wide, IN capabilities to serve a variety of access arrangements, from analog lines to wireless, and, in the future, to broadband and other high-speed optical links. Wyatt91 In addition to providing users with access to the network (if the SSP is a local exchange) and performing any necessary switching functionality, the SSP allows access to the set of IN capabilities. The SSP contains Detection Capability to detect requests for IN services. It also contains capabilities to communicate with other PEs containing SCF, such as SCP, and to respond to instructions from the other PEs. Functionally, an SSP

4.3.1.1.3SCP Functionally, an SCP contains Service Control Function (SCF) and optionally also Service Data Function (SDF). The SCF is implemented in Service Logic Programs (SLP). The SCP is connected to SSPs by a signalling network. Multiple SCPs may contain the same SLPs and data to improve service reliability and to facilitate load sharing between SCPs. In case of external Service Data Point (SDP) the SCF can access data through a signalling network. The SDP may be in the same network as the SCP, or in another network. The SCP can be connected to SSPs, and optionally to IPs, through the signalling network. The SCP can also be connected to an IP via an SSP relay function. Q1201

contains a Call Control Function, a Service Switching Function, and, if the SSP is a local exchange, a Call

The SCP comprises the SCP node, the SCP platform, and

Control Agent Function. It also may optionally contain

applications. The node performs functions common to

Service Control Function, and/or a Specialized Resource

applications, or independent of any application; it

Function, and/or a Service Data Function. The SSP may

provides all functions for handling service-related,

provide IN services to users connected to subtending

administrative, and network messages. These functions

Network Access Points. Q1201

include message discrimination, distribution, routing, and network management and testing. For example, when the

The SSP is usually provided by the traditional switch manufacturers. These switches are programmable and they can be implemented using multipurpose processors. The main difference of SSP from an ordinary switch is in the software where the service control of IN is separated

SCP node receives a service-related message, it distributes

the

incoming

message

the

proper

application. In turn, the application issues a response message to the node, which routes it to the appropriate network elements. Ambro89

from the basic call control. The SCP node gathers data on all incoming and outgoing messages to assist in network administration and cost

4.3.1.1.2NAP A NAP ( Network Access Point) is a PE that includes only the CCAF and CCF functional entities. It may also be present in the network. The NAP supports early and

allocation. This data is collected at the node, and transmitted to an administrative system for processing. Ambro89

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The SCP node also measures the frequency of SCP

4.3.1.1.6SN

hardware and software failures, resource usage, overload

The Service Node can control IN services and engage in

counts, and so on. It provides information needed to

flexible information interactions with users. The SN

perform maintenance procedures, thus minimizing the

communicates directly with one or more SSPs, ech with a

impact of failures on system performance. The node may

point-to-point

take action to prevent and correct the overload at the node

Functionally, the SN contains an SCF, SDF, SRF, and an

or at a particular application. Ambro89

SSF/CCF. This SSF/CCF is closely coupled to the SCF

signalling

and

transport

connection.

within the SN, and is not accessible by external SCFs. Q1201

4.3.1.1.4AD The Adjunct (AD) PE is functionally equivalent to an SCP (i.e. it contains the same functional entities) but it is directly connected to and SSP. Communication between and Adjunct and an SSP is supported by a high speed interface. This arrangement may result in differing performance characteristics for an adjunct and an SCP. The application layer messages are identical in content to those carried by the signalling network to an SCP. Q1201 An Adjunct may be connected to more than one SSP and an SSP may be connected to several Adjuncts.

In a manner similar to an Adjunct, the SCF in an SN receives messages from the SSP, executes SLPs, and sends messages to the SSP. SLP in an SN may be developed by the same Service Creation Environment used to develop SLPs for SCPs and Adjuncts. The SRF in an SN enables the SN to interact with users in a manner similar to an IP. An SCF can request the SSF to connect a user to a resource located in an SN that is connected to the SSP from which the service request is detected. An SCF can also request the SSP to connect a user to a resource located in an SN that is connected to an another

4.3.1.1.5IP

SSP. Q1201

The IP provides resources such as customized and concatenated voice announcements, voice recognition, and

Dual

Tone

Multi-Frequencies

(DTMF)

digit

collection, and contains switching matrix to connect users to these resources. The IP supports flexible information interactions

between

user

and

the

network.

Functionally, the IP contains the Special Resource Function. The IP may directly connect to one or more SSPs, and/or may connect to the signalling network. Q1201

4.3.1.1.7SSCP The SSCP (Service Switching and Control Point) is a combined SCP and SSP in a single node. Functionally, it contains an SCF, SDF, CCAF, CCF, and SSF. The connection between the SCF/SDF functions and the CCAF/CCF/SSF functions is proprietary and closely coupled, but it provides the same service capability as an SSP and SCP separately. This node may also contain SRF functionality, i.e. SRF as an optional functionality. The

An SCP or Adjunct can request an SSP to connect a user to a resource located in an IP that is connected to the SSP from which the service request is detected. An SCP or

interfaces between the SSCP and other PEs are the same as the interfaces between the SSP and other PEs, and therefore will not be explicitly stated. Q1201

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4.3.1.1.8SDP

subscriber personnel gain interactive messages to the

The SDP contains the customer and network data which

system. Ambro89

accessed

during

the

execution

service.

Functionally, the SDP contains an SDF. Q1201 It contains data used by Service Logic Programs to provide individualized services. Functionally, and SDP contains a Service Data Function. It can be accessed directly by an SCP and/or SMP, or through the signalling network. It can also access other SDPs in its own or other networks.

4.3.1.1.10

SCEP

The Service Creation Environment Point is used to define, develop, and test an IN service, and to input it into the SMP. Functionally, it contains the Service Creation Environment Function. The SCEP interacts directly with the SMP. Q1201

Q1201 4.3.1.1.11 4.3.1.1.9SMP

The Service Management Access Point provides some

The Service Management Point/Service Management System performs service management control, service provision control, and service deployment control. Examples of functions it can perform are database administration, network surveillance and testing, network traffic

management,

SMAP

and

network

data

collection.

selected users, such as service managers and customers, with access to the SMP. One possible use of the SMAP is to provide one single point of access for a given user to several SMPs. The SMAP functionally contains a Service Management Access Function. The SMAP directly interacts with the SMP. Q1201

Functionally, the SMP contains the Service Management Function and, optionally, the Service Management Access Function and the Service Creation Environment

4.3.1.2 Interfaces between PEs

Function. The SMP can access all other Physical Entities.

In the Physical Plane Architecture several standardized

Q1201

interfaces are stated. These interfaces are: SCP-SSP, ADSSP, IP-SSP, SN-SSP, SCP-IP, AD-IP, and SCP-SDP.

A Service Management System is the operations system through which network operator and service subscriber

Existing lower layer protocols are proposed for these

personnel manage SCPs and related service applications

candidate interfaces to carry the application layer

(programs and databases) in an IN. More than one SMS

messages required by IN services. As such, the focus of

may be associated with the IN; the network operating

the standardization effort for CS-1 is on the applications

company may want a separate SMS for each IN service or

layer protocols. At the application layer, the message sent

a single SMS for several IN services. Ambro89

that the different interfaces carry should reflect the same semantic content, even though the application layer

Physically, the SMS resides in a multipurpose computer.

message may be encoded or formatted differently. For

Processing power and database size requirements

example, the messages between the SSF in an SSP and

normally govern the choice of a specific computer. The

the SCF in an SCP, Adjunct or SN should contain the

SMS manages a private network consisting of switched

same information. The following sections give some

and leased line connected to a set of keyboard or display

proposed protocols for use on these interfaces. Q1201

terminals through which network operator and service

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4.3.1.2.1SCP-SSP interface

Q.931. This possibility provides for the flexibility to

The proposed underlying protocols platform for the

convey application layer information without affecting

interface between an SCP and an SSP is Transaction

the connection state of the call. Q1201

Capabilities Application Part (TCAP) on Signalling Connection Control Part (SCCP)/Message Transfer Part (MTP) of SS7. Q1201 So, the SCP-SSP interface in CS-1 is using CCITT SS7 protocol stack to communicate (signal) with each other. The interface could also be something else at the lowest layer protocols of the SS7 in order to achieve, for example, high-speed signalling between these PEs. That is why, the IN standardization is mainly focused on the application layer protocols.

4.3.1.2.4SN-SSP interface The proposed underlying protocol platform for the interface between an SN and an SSP is ISDN BRI, PRI (or both). An SN and an SSP exchange application layer messages over an ISDN D-channel using common element procedures of CCITT Recommendations Q.932. This communication may occur on a separate D-channel from the channel that carries the common element procedure messages. These channels may also be

4.3.1.2.2AD-SSP interface

separate. Q1201

The proposed underlying protocol platform for the ADSSP interface is TCAP. The physical interface has not been specified, but a number of alternative standard protocols could be used.

4.3.1.2.5SCP-IP interface The proposed underlying protocol platform for an interface between an SCP and an IP is TCAP on SCCP/MTP of the SS7 protocol stack. Q1201

4.3.1.2.3IP-SSP interface This interface is used for communications between an IP and an SSP as well as for communication between an IP and an SCP which is being relayed through an SSP. The proposed underlying protocol platform for the interface between an IP and an SSP is ISDN Basic Rate Interface

4.3.1.2.6AD-IP interface The proposed underlying protocol platform between an AD and an IP is TCAP. The physical interface has not been specified, but a number of alternative standard protocols could be used. Q1201

(BRI), Primary Rate Interface (PRI) (or both), or SS7. Q1201 4.3.1.2.7SCP-SDP interface If a BRI or PRI is used, the ISDN D-channel connecting

The proposed underlying protocol platform for the

an IP to an SSP carries application layer information

interface between an SCP and an SDP is TCAP on

between an SCF and an SRF, and supports the setup of B-

SCCP/MTP of SS7 protocol stack. In existing systems

channel connections to the IP. Information is passed from

the SCP - SDP interfaces have been implemented in

an SCF to an SRF (e.g. collected information and billing

many proprietary ways, a typical one being a fast remote

measurements) is embedded in the Facility Information

operations protocol using a Local Area Network (LAN).

Element (FIE). The FIE can be carried by a number of

Q1201

Q.931 messages, like SETUP and DISCONNECT. The FIE can also be carried by the FACILITY message in

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4.3.1.2.8User interfaces

Functional Entities are referred to as relationships (rN).

A user is an entity external to the IN that uses IN

The functional entities are described independently of

capabilities. IN users may employ the access interfaces

how the functionality is physically implemented or

described below to invoke various IN service capabilities.

deployed in the network. SIB’s on the global functional

For example, users can affect the routing of a call, send

plane are realized on the Distributed Functional Plane by

and receive information from the network, screen calls,

a sequence of Functional Entity Actions (FEA) and

and update service parameters. Users are served by

resulting information flows. Garra93

existing network interfaces. Q1201 It is important to ensure that IN should continue to support existing services and capabilities. In addition, the current restrictions imposed by each of the interface technologies described below must be considered when deploying IN services. For example, calling party information may or may not be available at a given interface and, therefore, may or may not be provided to the SCF. Q1201 End users are using analogue interface signalling, or ISDN access signalling arrangements. IN user-network interactions include providing stimuli, such as off-hook or

Figure 4-6. Distributed functional plane architecture.

DTMF digit signalling, which determine further IN

The DFP architecture provides flexibility to support a

action. Q1201

large variety of services and facilitates the evolution of IN

Out-of-band (i.e. D_channel) signalling provides ISDN users with additional capabilities for accessing potential IN services. When originating a call, an ISDN user identifies the bearer capability to be associated with the call. IN service logic can use this information to determine how the call should be handled (e.g. how to route the call). Q1201

by organizing the functional capabilities in an open-ended and modular strtucture to achieve service independence. The

DFP

architecture

vendor/implementation

independent, thereby providing the flexibility for multiple physical networking configuration and placing no constraints on national network architecture beyond the network and interface standards which will be developed for IN structured networks. The definition of the DFP architecture initially accomodates service execution

4.3.2

Distributed Functional Plane

capabilities and will accomodate service creation and

The global Distributed Functional Plane (DFP) is of

service and network management capabilities when they

primary interest to network designers and providers. It

become available. Q1201

describes the functional architecture of an IN-structured network in terms of units of network functionality (Figure

A Functional Entity is a unique group of functions in a

4-6). These functionalities are referred to as Functional

single location and a subset of the total set of functions

Entities (FE). The information that flows between

required to provide a service. One or more Functional

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Entities can be located in the same Physical Entity.

4.3.2.1.2CCF

Different Functional Entities contain different functions,

The CCF is the Call Control Function in the network that

and may also contain one or more of the same functions.

provides call/connection processing and control. It Q1201

In addition, one Functional Entity cannot be split between two Physical Entities; the Functional Entity is mapped entirely within a single Physical Entity. Finally, duplicate instances of a FE can be mapped to different PEs, though

establishes, manipulates and releases call/connection instances as “requested”

not the same PE. Q1201

by the CCAF; b)

provides the capability to associate and

4.3.2.1 Definition of FEs

relate CCAF functional entities that are

This section gives a description of the Functional Entities

involved in a particular call and/or

at the Distributed Functional Plane related to IN service

connection instance (that may be on SSF

execution and how they are mapped to the Physical Plane

requests);

architecture.

4.3.2.1.1CCAF The CCAF is the Call Control Agent Function that

manages the relationship between CCAF

provides access for users. It is the interface between user

functional entities involved in a call (e.g.

and network call control functions. It has the following

supervises the overall perspective of the

characteristics: It Q1201

call and/or connection instance);

provides for user access, interacting

functionality (e.g. passes events to the

with the user to establish, maintain, modify and release, as required, a call or instance of service; b)

accesses

the

capabilities

service-providing the

Call

Control

Function, using service requests (e.g.

provides trigger mechanism to access IN SSF);

is managed, updated and/or otherwise administred for its IN-related functions (i.e. trigger mechanisms) by a Service Management Function;

setup, transfer, hold, etc.) for the

4.3.2.1.3SSF

establishment, manipulation and release

The SSF is the Service Switching Function, which,

of a call or instance of service;

associated with the CCF, provides the set of functions

receives indications relating to the call

required for interaction between the CCF and Service

or service from the CCF and relays

Control Function. It Q1201

them to the user as required; d)

maintains call/service state information as perceived by this functional entity;

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extends the logic of the CCF to include

provides the SCF with access to SSF/CCF capabilities

recognition of service control triggers

and resources. It also detects IN call/connection

and to interact with the SCF;

processing events that should be reported to active IN

manages signalling between the CCF

service logic instances, and manages SSF resources

and the SCF;

required to support IN service logic instances. The IN-SM

modifies

call/connection

processing

functions (in the CCF) as required to process requests for IN provided service usage under the control of the SCF; d)

is managed, updated and/or otherwise administred by an SMF;

interacts with the FIM/CM as described below. c) FIM/CM - The entity in the SSF that provides mechanisms to support multiple concurrent instances of IN service logic instances on a single call. In particular, the FIM/CM can prevent multiple instances of IN an non-IN service logic instances from being invoked. The ability of the FIM/CM to arbitrate between multiple instances of IN and non-IN service logic instances is for further study. The FIM/CM integrates these interactions mechanisms with the BCM and IN-FM to provide the

4.3.2.1.4SSF/CCF Model

SSF with a unified view of call/service processing

The SSF/CCF model described below include the Basic

internal to the SSF for a single call.

Call Manager (BCM), the IN-Switching Manager (INSM), the Feature Interactions Manager (FIM)/Call

d) BCM Relationship to IN-SM - The relationship that

Manager (CM), the relationship of the BCM to the IN-

encompasses the interaction between the BCM and the

SM, the relationship of the BCM and IN-SM to the

IN-SM, through the FIM/CM. The information flow

FIM/CM, and the functional separation provided in the

related to this interaction is not externally

SSF/CCF (Figure 4-7). [Q1214]

not standardized for CS-1. However, an understanding of

visible and is

this subject is required to identify how basic call and a) BCM - The entity in the CCF that provides basic call

connection processing and IN call/connection processing

and connection control to establish communication paths

may interact.

for users and interconnects such communication paths, that detects basic call and connection control events that

e) BCM and IN-SM Relationships to FIM/CM - The

can lead to the invocation of IN service logic instances or

relationships that encompass the interaction between the

should be reported to active IN service logic instances,

BCM and FIM/CM, and the IN-SM and the FIM/CM.

and that manages CCF resources required to support basic

The information flows related to these interactions are not

call and connection control. The BCM interacts with the

externally visible and are not standardized for CS-1.

FIM/CM as described in the FIM/CM description below.

However, an understanding of this subject is required in order to unify the BCM, IN-SM and FIM/CM.

b) IN-SM - The entity in the SSF that interacts with the SCF in the course of providing IN service features to

f) Functional Separation in the SSF/CCF. The functional

users. It provides the SCF with an observable view of

separation of processes and resources in the SSF/CCF

SSF/CCF call/connection processing activities, and

that provides a means of handling service logic instance interactions for CS-1. This functional separation services

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to isolate single-ended service logic instances related to

representation of CCF activities that can be analysed to

the calling party from single-ended service logic instances

determine which aspects of the BCSM will be visible to

related to the called party for the same call. Within the

IN service logic instances, if any, and what level of

scope of CS-1, there is no functionality in the SSF for

abstraction and granularity is appropriate for this

handling service feature interactions between the separate

visibility.

SSF calling party processes and SSF called party The BCSM identifies points in basic call and connection

processes.

processing when IN service logic instances are permitted to interact with basic call and connection control capabilities. In particular, it provides a framework for SCF

describing basic call and connection events that can lead

SLPI A

to the invocation of IN service logic instances or should be reported to active IN service logic instances, for describing those points in call and connection processing

SSF IN Local Resource Data Manager IN Local Resource data Non-IN Feature Manager

CCF SRF

CCAF

Basic Call Resource data Manager

Basic Call Resource data

SCF Access Manager

at which these events are detected, and for describing

IN-SM

those points in call and connection processing when the

IN Switching State Model Instance < IN-SSM > > IN-SSM Events > < REsource Control >

transfer of control can occur.

FIM/CM

Figure 4-8 shows the key components that have been

BCM Basic Call Manager < BCSM > < Basic Call Triggers > < Basic Call Events >

identified to describe a BCSM, to include: Points in Call (PICs), Detection Points (DPs), transitions, and events. PICs identify CCF activities required to complete on or

Bearer Control

CCAF

more basic call/connection states of interest to IN service logic instances. DPs indicate points in basic call and

Figure 4-7. SSF/CCF Model

connection processing at which transfer of control can occur. Transitions indicate the normal flow of basic

4.3.2.1.4.1

BCSM

call/connection processing from one PIC to another.

The BCSM is a high-level finite state machine description

Events cause transitions into and out of

PICs.

of CCF activities required to establish and maintain

Information Flows [Q1214] (e.g. between SSF/CCF and

communication paths for users. As such, it identifies a set

SCF) corresponding to Events and PICs are represented

of basic call and connection activities in a CCF and

shows how these activities are joined together to process

Service Elements (ASEs), these application protocol

a basic call and connection (i.e., establish and maintain a

related concepts are discussed in more detail in chapter

communication path for a user). [Q1214]

4.4.3.

Many aspects of the BCSM are not externally visible to

The BCSM for CS-1 should model existing switch

IN service logic instances. However, aspects of BCSM

processing of basic two-party calls, and should reflect the

will be the subject of standardization. As such, the BCSM

functional separation between the originating and

is primarily an explanatory tool for providing a

terminating portions of calls. In addition, though CCAF

Operations [Q1218] and modelled as Application

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functionality is not explicitly modelled in the BCSM, a

originating half of the BCSM are described below

mapping is required between access signalling events and

[Q1214]:

BCSM events, for each access arrangement supported by 1)

CS-1. Since the BSCM is generic, it may describe events that do not apply to certain access arrangements. It is important to understand and describe how each access arrangement applies to the BCSM.

O_Null&Authorize_Origination_Atempt

Entry Event: Disconnect and clearing of a previous call (DPs 9 0_Disconnect and 10 - O_Abandon), or default handling of exeptions by SSF/CCF completed.

Functions:

- Interface (line/trunk) is idled (no call exists, no call reference exists, etc.) Supervision is being provided. O_Abandon 1. O_Null & Authorize Origination attempt

6. Exception

- Given an indication from an originating party of a desire to place an outgoing call (e.g., offhook, Q.931 Setup message, ISDN-UP IAM

Orig. Attempt_Authorized

message), the authority/ability of the party to place the call with given

2. Collect Info

properties (e.g., bearer capability, line restrictions) is verified. The types 2

of authorization to be performed may vary for

Collected_Info

O_Disconnect

Exit Event:

Analyzed_Info

4. Routing & Alerting

Route_Select_Failure 5

- Indication of desire to place outgoing call (e.g., offhook, Q.931 Setup message, ISDN-UP IAM message) and authority/ability to place

O_Called_Party_Busy

outgoing call verified (DP 1 - Origination_Attempt_Authorized)

5. O_Active

types

of originating resources (e.g., for lines vs. trunks).

3. Analyze Info

different

6 O_No_Answer

8 O_Mid_Call

Key:

- Authority/ability to place outgoing call denied (Exception) Corresponding Q.931 Call State: 0. Null

Transition Detection Point (DP)

Collect_Information

Point in Call (PIC)

Entry Event: Indication of desire to place outgoing call (e.g., offhook,

Figure 4-8. Originating BCSM for CS1

Q.931 Setup message, ISDN-UP IAM message) and authority/ability to place outgoing call verified (DP1-Origination_Attempt_ Authorized)

4.3.2.1.4.2

Originating BCSM for CS-1

Functions:

As an axample we describe here the originating half of the BCSM for CS1. It corresponds to that portion of the

- Initial information package/dialling string (e.g., service codes,

BCSM associated with the originating party (see Figure

prefixes, dialled address digits) being collected from originating party.

4-8). The description for each of the PICs in the

Information being examined according to dialling plan to determine end of collection. No further action may be required if an en bloc signalling

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method is in use (e.g., an ISDN user using en bloc signalling, an

- Routing address and call type being interpreted. The next route is

incoming SS No. 7 trunk).

being selected. This may involve sequentially searching a route list, translating a directory number into physical port address, etc. The

Exit Events:

individual destination resource out of a resource group (e.g., a multi-line

- Availability of complete initial information package/dialling string from originating party. (This event may have already occurred in the case of en bloc signalling, in which case the waiting duration in this PIC is zero.) (DP 2- Collected_Info)

hunt group, a trunk group) is not selected. In some cases (e.g., an analogue line interface), a single resource (not a group) is selected.

- Authority of originating party to place this particular call being verified (e.g., checking business group restrictions, toll restrictions, route restrictions). The types of authorization checks to be performed

- Originating party abandons call. (10 - O_Abandon)

may depend upon the type of originating resource (e.g., line vs. trunk). - Information collection error has occurred (e.g., invalid dial string - Call is being processed by the terminating half BCSM. Continued

format, digit collection time-out) (Exception)

processing of call setup (e.g., ringing, audible ring indication) is taking 3)

place. Waiting for indication from terminating half BCSM that the call

Analyze_Information

has been answered by terminating party. Entry

Event:

Availability

complete

initial

information

package/dialling string from originating party. (DP 2 - Collected_Info)

Exit Events:

Function: Information being analysed and/or translated according to

- Indication from the terminating half BCSM that the call is accepted

dialling plan to determine routing address and call type (e.g., local

and answered by terminating party (e.g., terminating party goes offhook.

exchange call, transit exchange call, international exchange call).

Q.931 Connect message received. ISDN-UP Answer message received) (DP 7 - O_Answer)

Exit Events: - Unable to select a route (e.g., unable to determine a correct route, no - Availability of routing address and nature of address. (DP 3 Analyzed_Info)

that call cannot be presented to the terminating party (e.g., network

- Originating party abandons calls. (DP 10 - O_Abandon)

- Unable to analyse and translate dial string in the dialling plan (e.g.,

congestion) (DP 4 - Route_Select_Failure)

- Indication from the terminating half BSCM that the terminating party is busy (DP 5 - O_Called_Party_Busy)

invalid dial string) (Exception)

more routes on route list) or indication from the terminating half BCSM

- Indication from the terminating half BCSM that the terminating party

Routing and Alerting

does not answer within a specified time period (DP 6 - O_No_Answer) (encompasses the following general BCSM PICs: Select_Route, Authorize_Call_Setup, Call_Sent, and O_Alerting)

- Originating party abandons call (DP 10 - O_Abandon)

- Authority of calling party to place thiscall is denied (e.g., business

Entry Events:

group restriction mismatch, toll restricted calling line) (Exception) - Availability of routing address and call type. (DP 3 - Analyzed_Info) Corresponding Q.931 Call State: 4. Call Delivered Functions:

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- The SSF/CCF should make use of vendor-specific procedures to

O_Active

ensure release of resources within the SSF/CCF so that line, trunk, and Entry Event: Indication from the terminating half BCSM that the call is

other resources are made available for new calls.pt PIC).

accepted and answered by terminating party. (DP 7 - O_Answer) Exit Event: Default handling of the exception condition by SSF/CCF Function: Connection established between originating and terminating

completed (Transition to O_Null & Authorize_Origination_Attempt)

party. Message accounting/charging data may be being collected. Call supervision is being provided.

4.3.2.1.5SCF Exit Events:

The SCF is a function that commands call control

- A service/service feature request is received from the originating party (e.g., TDMF, hook flash, ISDN feature activator, Q.931 HOLD or RETrieve message). (DP 8 - O_Mid_Call)

- A disconnect indication (e.g., onhook, Q.931 Disconnect message, SS7 Release message) is received from the originating party. or received from the terminating party via the terminating half BCSM. (DP -

functions in the processing of IN provided and/or custom service requests. The SCF may interact with other functional entities to access additional logic or obtain information (service or user data) required to process a call/service logic instance. It. Q1201 a)

interfaces and interacts with SSF/CCF, SRF and SDF functional entities;

O_Disconnect)

contains

the

capability

- A connection failure occurs (Exception)

logic

required

and to

processing handle

provided service attempts; 6)

O_Exception

if necessary;

Entry Event: An exception condition is encountered (as described above

for each PIC)

interfaces and interacts with other SCFs,

is managed, updated and/or otherwise administered by an SMF;

Function: Default handling of the exception condition is being provided. This includes general actions necessary to ensure no resources remain

4.3.2.1.6SDF

inappropriately allocated, such as

The SDF contains customer and network data for real time access by the SCF in the execution of an IN

- If any relationships exist between the SSF and SCF(s), send an Error

provided service. It Q1201

information flow to the SCF(s) closing the relationships and indicating that any outstanding call handling instructions will not run to completion (e.g., see Annex B).3

- If an SCF previously requested that call parameters be provided at the end of the call (see the Call Information Request information flow in section 6), these should be included in the Error information flow.

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interfaces and interacts with SCF as

4.3.2.1.10

required;

This function allows deployment and provision of IN

interfaces and interacts with other SDFs,

provided services and allows the support of ongoing

if necessary;

operation. Particularly, for a given service, it allows the

is managed, updated and/or otherwise

coordination of different SCF and SDF instances Q1201.

SMF

administered by an SMF; a)

billing and statistic information are

4.3.2.1.7SRF

received from the SCFs, and made

The SRF provides the specialized resources required for

available to authorized service managers

the execution of IN provided services (e.g. digit receivers,

through the SMAF;

announcements, conference bridges, etc.). It Q1201

modifications

service

data

are

distributed in SDFs, and it keeps track of the reference service data values; a)

interfaces and interacts with SCF and SSF (and with the CCF);

The SMF manages, updates and/or administers service

is managed, updated and/or otherwise

related information in SRF, SSF and CCF Q1201.

administered by an SMF; 4.3.2.1.11 c)

SCF Model and its relations

may contain the logic and processing

The model of the Service Conrol Function and its relation

capability to receive/send and convert

to other functional entities is shown in Figure 4-9. The

information received from users;

prime function of SCF is the execution of Service Logic

may contain functionality similar to the

provided in the form ofService Logic Processing

CCF to manage bearer connections to

programs (SLPs), and it includes also the SLP execution

the specialized resources;

supporting

functions,

selection/interaction

such

management,

Service

Logic

functional

entity

4.3.2.1.8SCEF

access management and SLP provisioning managemant.

This function allows services provided in Intelligent

[Q1214]

Network to be defined, developed, tested an input to SMF. Output of this function would include service logic, service management logic, service data template and service trigger information. Q1201

The SCF platform provides a Service Logic Execution Environment (SLEE) on which the SLPs run to provide service processing.

An SLP is a service application

program invoked by the SLEE and is used to realize service processing under the control of of thr SLEE. The

4.3.2.1.9SMAF

Service Logic Execution Manager (SLEM) is the

This function provides an interface between service

functionality of SLEE that handles and controls the

managers and the SMF. It allows service managers to

service logic execution action.

It contains the SLP

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Instances (SLPIs), Service Logic Selection/Interaction

PE:s

SCF

Manager and Resource Manager.

SCP

SSP

SLPI is a service application program instance invoked by the SLEE and is used to realize service processing. SLPI is a dynamic entity that actively controls the flow of routines. Functional routines are the functionality of SCF

SDP

to cause a sequence of Functional Entity Actions. This

SSCP

sequence

NAP

Functional Entity Actions provides the

functionality defined for a Service Independent Building Block (SIB) on the Global Functional Plane. The SIB concept will be discussed in more detail in chapter 4.3.3.1.

SDF

SRF

C C

O C

service execution and invokes other SCF functional

SSF/CCF

C C

C (CCF only)

C: Core O: Optional : Not allowed Table -4. Typical scenarios of FE to PE mapping.

SCF

4.3.3

SLP Library

Global Functional Plane

The Global Functional Plane (GFP) is of primary interest Service Logic Execution Environment (SLEE)

SLP Manager

Service Logic Execution Manager

Functional Routine Mgr

Functional Routine Lib.

Serv. Logic Selection/ Interaction Manager

SCF Data Access Manager + SD Obj.Lib + Ntw Res.Data

SLP Instances Resource Manager

to service designers. Wyatt91 The Global Functional Plane plane models network functionality from a global, or network-wide, point of view. As such, the IN structured network is said to be viewed as a single entity in the GFP. In this plane, services and Service Features

Functional Entity Access Manager

are redefined in terms of the broad network functions required to support them. These functions are neither SMF

SSF

SRF

SDF

service nor Service Feature specific and are referred to as SIB’s (Service-Independent building Block). Q1201

Figure 4-9. SCF Model Services identified in the service plane are decomposed 4.3.2.2 Mapping FEs to PEs The mapping of Distributed Functional Plane FEs to Physical Plane Architecture PEs is described here. Also a typical scenario of such mapping is shown here. (Table -

into their service features then mapped onto one or more SIBs in the GFP. Each SIB is similarly mapped onto one or more FEs in the Distributed Functional Plane Q1201 (Figure 4-10).

4) Q1201

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SIBs are defined completely independent from any physical architecture considerations Each SIB has a unified and stable interface, with one or more inputs an one or more outputs SIBs are reusable, monolithic, building blocks, describing a single complete activity, and used by the service designer to create services A SIB can exist independently, or it can coexist with other SIBs in the same network element. IN-based services can be distinguished from one another by the sequence of SIB functions and by the specific parameters within each SIB.

IN CS1 describes 13 SIBs plus a

specialized SIB called Basic Call Process (Table -5). Algorithm

Screen

Charge

Service Data Management

Compare

Status Notification

Distribution

Translate

Limit

User Interaction

Log Call Information

Verify

Queue Figure 4-10. Service decomposition.

Table -5 The CS1 SIBs.

4.3.3.1 SIB

Basic Call Process (BCP) identifies the normal call

IN CS1 contains 14 SIB’s that include algorithm, charge,

process from which IN services are launched, including

compare, translate, basic call process, among others. In

Points Of Initiation (POI) and Points Of Return (POR)

principle many other services described in CCITT

which provide the interface from the BCP to Global

Recommendations Q.1211 could be specified. Raat93

Service Logic (GSL). The GSL describes how SIBs are

SIBs are standard reusable networkwide capabilities

chained together to describe Service Features. The GSL

residing in the Global Functional Plane, used to create

also describes interaction between the BCP and the SIB

services. As such they are global in nature and their

chains. Q1201 (Figure 4-11) By definition, SIBs,

locations need not to be considered as the entire network

including the BCP, are service independent and cannot

is regarded as a single entity. A Service Feature is

contain knowledge of subsequent SIBs. Therefore, GSL

provided by a combination of one or more SIBs. SIBs

is the only element in the GFP which is specifically

have the following characteristics:

service dependent.

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to specify subscriber specific details like calling or called line information. This data can be: made available from the

Basic

Call

Process

SIB

(e.g.

Calling

Line

Identification), generated by a SIB (e.g. translated number), or entered by the subscriber (e.g. dialled number or a PIN code). Q1201 Figure 4-11. Modelling of Global Functional Plane.

Associated with each CID value is a logical name which

In order to chain SIBs together, knowledge of the

is referred to as the CID Field Pointer (CIDFP). If a SIB

connection pattern, decision options, and data required by

requires CID to perform its function, there will be an

SIBs must be available. Therefore, the pattern of how SIB

associated CIDFP assigned through SSD. For instance,

are chained together must be maintained within the GFP,

the Translate SIB’s CID which defines what is to be

and described in the GSL. The GSL described

translated is called Information. Q1201

subsequential SIB chaining, potential branching, and where branches rejoin.When an IN supported service is to be invoked, its GSL is laucnhed at the POI by a triggering mechanism from the BCP. At the end of chain of SIBs, the GSL also describes returning point to the BCP by indicating the specific POR. For a given service or Service Feature at least one POI is required. However, depending upon the logic required to support the service or Service Feature, multiple PORs may be defined.

Since the CID value can vary with each call instance, Service Features can be written with data flexibility. In the above Translate SIB example, one Service Feature may require translation of a calling number, while another Service Feature will require translation of the called number. In both cases, the data required by the SIB is specified by the information Calling Line Identity (CLI), but the CIDFP-info changes. Q1201

Q1201 4.3.3.1.2Service Support Data In order to describe Service Features with these generic SIBs, some elements of service dependency is needed. Service dependency can be described using data parameters which enable a SIB to be tailored to perform the desired functionality. Data parameters are specified

Service Support Data defines data parameters required by a SIB which are specific to the Service Feature description. When a SIB is included in the GSL of a service description, the GSL will specify the SSD values for the SIB. SSD consists of the following parts: Q1201

independently for each SIB and are made available to the SIB through GSL. Two types of data parameters are required for each SIB, dynamic parameters called Call Instance Data (CID) and static parameters called Service Support Data (SSD). Q1201

4.3.3.1.1Call Instance Data Call Instance Data defines dynamic parameters whose value will change with each call instance. They are used

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Fixed Parameters

parameters

one or more logical end points and CID which defines

whose values are fixed for all

data parameters specific to that call instance which results

call instances. For instance, the

from the execution of that SIB and are required by other

“File Indicator” SSD for the

SIBs or the BCP to complete the call service instance.

These

are

data

Translate SIB need to be specified uniquely for each occurrence of that SIB in a given Service Feature. The “File Indicator” SSD value is then said to be fixed, as its value is determined by the service/Service

Feature

description, not by the call instance. Field Pointers

Field Pointers identify which CID is required by the SIB, and in doing so provide a logical location for that data. They are signified

“CIDFP-xxxx”

where “xxxx” names the data required.

For

instance,

“CIDFP-info” for the Translate SIB will specify which CID element is to be translated. If more than one CID is required by a SIB to perform its function, then the SSD data parameters

will

Figure 4-12. Graphic representation of a SIB. Q1201 4.3.3.1.3.1

Queue SIB

As an example of SIB representation the Queue SIB is described (Figure 4-12). Q1201 The Queue SIB example has been described, because it is a multipurpose SIB which can be used in several Service Features at the Service Plane. The task of the Queue SIB is to provide sequencing of IN calls to be completed to a called party. The Queue SIB provides all the processing needed to provide queueing for a call, and will specifically: pass the call if resources are available, queue the call, play announcements to a caller on queue, and when resources become available, dequeue the call.

contain

multiple Field Pointers.

4.3.3.1.3The SIB structure A SIB contructs of both input and output parts (Figure 411). The input part consists of three distinct elements: one logical starting point, Service Support Data which defines parameters which are specified by the service description, and Call Instance Data which are specific to that call instance. The output part consist of two distinct elements: Lappeenranta University of Technology and Telecom Finland

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Figure 4-13. The Queue SIB graphic representation.

SSD

- Max Active

The input parameters for the Queue SIB has been

Specifies the maximum number of active

described in the Table -6. The Queue SIB can be used

calls allowed for the resource.

everywhere the queueing of calls is needed. The Logical

- Max Number

Start indicates the execution for the SIB.

Specifies the maximum number of calls allowed on queue at a given time.

The output parameters are also specified in the Q1201.

- Max Time

The Logical End indicates the result of the execution. The

- Specifies the maximum time the call may

parameters for Queue SIB are: Resource available, Call

remain on the queue.

party abandon, Queue timer expiry, Queue full, and an

- Announcement Parameters

error. Q1201 The Call Instance Data has the following

Specify

parameters and the meanings of output data: Time Spent

announcements. The control values which

in Queue (identifies the total time that a particular call

can be specified are: Announcement ID

was queued), Error Cause (identifies the specific

(specifies which announcement is to be

condition which caused an error during the operation of

sent), Repetition Requested (specifies if the

the SIB). In Error Cause the following errors have been

announcement is to be repeated), Repetition

identified: Invalid Max Active, Invalid Max Number,

Interval (specifies the delay period in

Invalid Max Time, Invalid Announcement Parameters,

seconds between repetitions) and Maxium

and Invalid Call Reference.

Repetitions (specifies the maximum number of

the

times

the

control

values

announcement

for

will

repeated). - CIDFP-Resource This CID Field Pointer specifies which Call Instance Data identifies the resource. - CIDFP-Error This CID Field Pointer specifies where in output Call Instance Data the error cause will be written. CID

- Call Reference Identifies the specific call which is a candidate for queueing. - Resource Specifies the data associated with the CIDFP-Resource

which

identifies

the

resource for which the call will be queued. Table -6 Queue SIB input resources.

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4.3.3.2 Basic Call Process

Functional Entities

The Basic Call Process is responsible for providing basic

SIB

call connectivity between parties in the network. The

Algorithm

BCP can be viewed as a specialized SIB which then

Charge

provides basic call capabilities including connecting call

Compare

with appropriate disposition; disconnecting calls, with

Distribution

appropriate disposition; and retaining CID for further

Limit

processing of that call instance. Q1201

Log

The need for specific POI/POR functionality is that the same chain of SIBs may represent a different service if launched from a different point in the BCP. Similarly, the

SSF/SCF

SCF

SRF

SDF

Call

Information Queue Screen

same chain of SIBs launched from the same point may

Service

Data

represent a different service if returned to the BCP at a

Management

different point. Q1201

Status notification

4.3.3.3 Global Service Logic The Global Service Logic can be defined as the “glue” that defines the order in which SIBs will be chained together to accomplish services. Each instance of global service logic is (potentially) unique to each individual call, but uses common elements, comprising specifically:

Translate User Interaction Verify Basic

Call

Process Table -7. Relating the GFP to the DFP.

BCP interaction point (POI and POR); SIBs; logical connections between SIBs, and between SIBs and BCP interaction points; input and output data parameters,

4.3.4

service support data and call instance data defined for

The Service Plane (SP) is of primary interest to service

each SIB. Q1201 The GSL will then chain together these

users and providers. It describes services and Service

elements (SIBs) to provide a specific service.

Features from a user perspective, independent of how the

Service Plane

service is implemented or provisioned in the network. 4.3.3.4 Relating the GFP to the DFP

Garra93

This section describes the mapping of the elements of the

The Service Plane illustrates that IN supported services

Global Functional Plane to the Distributed Functional

can be described to the end user or subscriber by means

Plane. Functions in the GFP are distributed to Functional

of a set of generic blocks called Service Features. A

Entities in the DFP. These FEs are related by information

service

flows, which are use to send information between FEs.

characterized by one or more core Service Features, and

Table -7 shows the CS1 SIBs and indicates the FEs

can be optionally enhanced by other Service Features.

involved for each SIB. Q1201

Q1201

stand-alone

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* Automatic Call Back (ACB)

Closed User Group (CUG)

whatsoever regarding the implementation of the services

* Call Hold with Announcement (CHA)

Customer Profile Management (CPM)

* Call Transfer (TRA)

Customized Recorded Announcement (CRA)

* Call Waiting (CW)

Customized Ringing (CRG)

* Consultation Calling (COC)

Follow-Me Diversion (FMD)

* Meet-Me Conference (MMC)

Mass Calling (MAS)

* Multi-Way Calling (MWC)

Originating Call Screening (OCS)

The services are constructed of Services Features. A

ABbreviated Dialing (ABD)

Off-Net Access (OFA)

Service Feature is a specific aspect of a service that can

Attendant (ATT)

Off-Net Calling (ONC)

also be used in conjuntion with other services/Service

Authentication (AUTC)

One Number (ONE)

Features as a part of commercial offering. It is either a

Authorization Code (AUTZ)

Origin Dependent Routing (ODR)

Call Distribution (CD)

Originating User Prompter (OUP)

Call Hold with Announcement (CHA)

Personal Numbering (PN)

Call Forwarding (CF)

Premium Charging (PRMC)

Call Forwarding in BY/DA (CFC)

Private Numbering Plan (PNP)

Call Gapping (GAP)

Reverse Charging (REVC)

Call Limiter (LIM)

Split Charging (SPLC)

Call Logging (LOG)

Terminating Call Screening (TCS)

Call Queueing (QUE)

Time Dependent Routing (TDR)

The Service Plane represents an exclusively serviceoriented view. This view contains no information the

network

(for

instance,

type

implementation is invisible). All that is perceived is the network’s service-related behaviour as seen, for example, by a service user. Q1201 In other words, the Service Plane

provides

users

and

service

providers

implementation-independent architecture.

4.3.4.1 Service Features

core part of a service or an optional part offered as an enhancement to a service Q1201 (Table -8).

Note: The service indicated with a * may only be partially supported in CS1, because they require capabilities beyond those of type A services. Table -8. Set of Benchmark IN CS1 Service Features.

So, the services are comprised of one or more Service Features. A Service Feature is the smallest part of a

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service that can be perceived by the service user. These

Attendant (ATT)

SFs can also be used as building blocks in the This service feature allows VPN users to access an attendant

specification and design of new, more complex services. SFs are are comprised of one or more SIBs which are described in the Global Functional Plane. All individual telecommunication services identified in the Service Plane should be described as seen from the user’s

position within the VPN for providing VPN service information (e.g., VPN numbers). The attendant(s) can be accessed by dialling a special access code.

Authentication (AUTC)

viewpoint without reference how the services are implemented in the network (for example, how the

This service feature allows for the verification that a user is

Physical Plane looks like) Q1201. The Service Features

allowed to exercise certain options in a telephone network. In other

are described in detail in the next chapter.

words, the request made by the user is authentic and should be granted.

4.3.4.2 Description of CS1 Service Features

Authorization Code (AUTZ)

The CS1 Service Features are described in [Q1211] as This service feature allows a VPN user to override calling

follows:

restrictions of the VPN station from which the call is made. Abbreviated Dialling (ABD)

Different sets of calling privileges can be assigned to different authorization codes and a given authorization code can be shared

Description No.1 by multiple users. This feature allows the definition of abbreviated dialling Automatic Call Back (ACB) numbers with a VPN. For the users of the VPN, the abbreviated dialling numbers are not subjected to call restrictions, e.g., a VPN

This service feature allows the called party to automatically

user may not be allowed to access the Off-net Calling service

call back the calling party of the last call directed to the called

feature but can reach an off-net number via this feature.

party.

Description No. 2

Call Distribution (CD)

This feature allows the definition of abbreviated dialling digit

This service feature allows the served user to specify the

sequences to represent the actual dialling digit sequence, i.e., a two

percentage of calls to be distributed among two or more

digit sequence may represent a complete dialling sequence for a

destinations. Other criteria may also apply to the distribution of

private or public numbering plan.

calls to each destination.

Description No. 3

Call Forwarding (CF)

This service feature is an originating line feature that allows

This service feature allows the user to have his incoming

business subscribers to dial others in their company using a short

calls addressed to another number, no matter what the called party

numbering, even if the calling user's line and the called user's line

line status may be.

are served by different switches. Call Forwarding on Busy/Don't answer (CFC)

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This service feature allows the called user to forward

Call Logging (LOG)

particular calls if the called user is busy or does not answer within a This service feature allows for a record to be prepared each

specified number of rings.

time that a call is received to a specified telephone number. Call Gapping (GAP) Call Queueing (QUE) Description No. 1 Description No. 1 This service feature allows the service provider to automatically restrict the number of calls to be routed to the

This service feature allows a served user to have calls meeting busy at the scheduled destination to be placed in a queue

subscriber.

and connected as soon as free condition is detected. Upon entering Description No. 2

the queue, the caller hears an initial announcement informing the caller that the call will be answered when a line is available.

This service feature allows to restrict the number of calls to a served user to prevent congestion of the network.

Description No. 2

This service feature enables the subscriber, when a call

Call Hold with Announcement (CHA)

encounters a terminating trigger such as a busy condition or a The Call Hold with Announcement service feature allows a subscriber to place a call on hold with options to play music or

specified number of rings to queue that call, a specific announcement being sent to the calling party.

customized announcements to the held party. Call Transfer (TRA) Call Limiter (LIM) The Call Transfer service feature allows a subscriber to place Description No. 1

a call a hold and transfer the call to another location.

This service feature allows a served user to specify the

Call Waiting (CW)

maximum number of simultaneous calls to a served user's destination. If the destination is busy, the call may be routed to an alternative destination.

This service feature allows the called party to receive a notification that another party is trying to reach his number while he is busy talking to another calling party.

Description No. 2 Closed User Group (CUG) This service feature enables to count the sunning calls to the subscriber and to reject all the new calls when a threshold of

This service feature allows the user to be a member of a set

simultaneous calls is reached. As an option, this threshold may be

of VPN users who are normally authorized to make and/or receive

real-time managed by the subscriber.

calls only within the group. A user can belong to more than one CUG. In this way a CUG can be defined so that certain users are

Associated

with

Call

Volume

Distribution

Distribution, it allows the rerouting of the new calls.

Call

allowed wither to make calls outside the CUG, or to receive calls from outside the CUG, or both.

Consultation Calling (COC)

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The Consultation Calling service feature allows a subscriber

the user will be presented to this terminal access. A registration for

to place a call on hold, in order to initiate a new call for

incoming calls will cancel any previous registration. Several users

consultation.

may register for incoming calls to the same terminal access simultaneously. The user may also explicitly de register for

Customer Profile Management (CPM)

incoming calls.

This service feature allows the subscriber to real-time manage

his

service

profile,

i.e.,

terminating

Mass Calling (MAS)

destinations,

announcements to be played, call distribution, an so on.

This service feature allows processing of huge numbers of incoming calls. generated by broadcasted advertisings or games.

Customized Recorded Announcement (CRA) Meet-Me Conference (MMC) This service feature allows

a call to be completed to a

(customized) terminating announcement instead of

a subscriber

This service feature allows the user to reserve a conference

line. The served user may define different announcements for

resource for making a multi-party call. indicating the date, time, and

unsuccessful call completions due to different reasons (e.g., caller

conference duration. At the specified date and time, each participant

outside business hours, all lines are busy).

in the conference has to dial a designated number which has been assigned to the reserved conference resource, in order to have

Customized ringing (CRG)

access to that resource, and therefore, the conference.

This service feature allows the subscriber to allocate a

Multiway Calling (MWC)

distinctive ringing to a list of calling parties. This service feature allows the user to establish multiple, Destinating User Prompter (DUP)

This service feature enables to prompt the called party with a

simultaneous telephone calls with other parties.

Off-Net Access (OFA)

specific announcement. Such an announcement may ask the called party to enter an extra numbering, e.g., through Dual-Tone Multi-

This service feature allows a VPN user to access his or her

Frequency (DTMF), or a voice instruction that can be used by the

VPN from any non-VPN station in the PSTN by using a Personal

service logic to continue to process the call.

Identification Number (PIN). Different sets of calling privileges can be assigned to different PINs, and a given PIN can be shared by

Follow-Me Diversion (FMD)

Description No. 1

multiple users.

Off-Net Calling (ONC)

This service feature allows a VPN user to change the routing number of his/her VPN code via a DTMF phone. The updated number can be another VPN code or a PSTN number.

Description No. 2

This service feature allows the user to call outside the VPN network. Calls from one VPN to another are also considered offnet.

One Number (ONE)

With this service feature, a user may register for incoming calls to any terminal access. When registered, all incoming calls to

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This feature allows a subscriber with two or more

This service feature supports a UPT number that uniquely

terminating lines in any number of locations to have a single

identifies each UPT user and is used by the caller to reach that UPT

telephone number. This allows businesses to advertise just one

user. A UPT user may have more than one UPT

telephone number throughout their market area and to maintain

different applications (e.g., a business UPT number for business

their operations in different locations to maximize efficiency. The

calls and a private UPT number for private calls), however, a UPT

subscriber can specify which calls are to be terminated on which

user will have only one UPT number per charging account.

number for

terminating lines based on the area the calls originate. Premium Charging (PRMC) Origin Dependent Routing (ODR) This service feature allows for the pay back of the part of the This service feature enables the subscriber to accept or reject a call, and in case of acceptance, to route this call, according to the

cost of a call to the called party, when he is considered as a value added service provider.

calling party geographical location. This service feature allows the served user to specify the destination installation(s) according to the

Private Numbering Plan (PNP)

geographical area from which the call was originated.

Originating Call screening (OCS)

This service feature allows the subscriber to maintain a numbering plan within his private network, which is separate from the public numbering plan.

This service feature allows the served user to bar calls from certain areas based on the District Code of the area from which the

Reverse Charging (REVC)

call is originated.

This service feature allows the service subscriber