in tutorial

8/14/2019 In Tutorial

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Telecom FINLAND

Telecom research centre

Elimenkatu 9a

00510 Helsinki

finland

and

Lappeenranta university of technology

department of information technology

lappeenranta

Intelligent Network Tutorial

for the secondwinterSchool on telecommunications

march 1994

Abstract

The development of telecommunications techniques and the need for more advanced services hascreated 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 thedecisions on their own implementations. The first standard sets of IN are Bellcores AIN.0 and

the CCITTs Capability Set 1 (CS1). They define the basic services of IN and provide someadditional features such as rapid service introduction and a flexible architecture that provides

future expansion to further IN Capability Sets. The standardation organisations, such as CCITTand ETSI, work hard to help the service providers to implement their IN architecture flexible in

order to be able to provide international IN services. This kind of architecture is better known asglobal Intelligent Network architecture and it should be taken into consideration already in theearly implementations of IN. This paper provides some history of telecommunications

technology, an overview of IN and its services and some additional discussion on the futurebroadband IN.

Kim MolinLappeenranta University of technology

laserkatu 653850 Lappeenranta, Finland

E-mail: molinmato.cc.lut.fiTel.Int: +358 0 574 3625

Olli MartikainenTelecom research centre

sturenkatu 16 helsinkitelecom finlanD

Tel.int: +358 0 7098 3503


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Contents

Contents

Abbreviations

1. PREFACE 1

2. INTRODUCTION 2

2.1 Early computers and telecommunications 2

2.2 Switching systems development 3

2.3 Turning-points in telecommunications 5

2.3.1 UMTS 5

3. COMPUTER CONTROLLED TELECOMMUNICATIONS 7

3.1 CCITT Signalling System No. 7 7

3.1.1 Network Services Part 8

3.1.2 User Part 8

3.1.3 Signalling network structure 9

3.2 Telecommunications Management Network 9

3.2.1 Functional architecture 10

3.2.2 Informational architecture 11

3.2.3 Physical architecture 12

3.3 The need for IN 12

3.3.1 Mobility and users identification 12

4. INTELLIGENT NETWORK ARCHITECTURE 14

4.1 Overview of IN 14

4.2 IN standardation 16

4.2.1 IN standards bodies 16


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4.2.2 Phased standardation 16

4.2.3 Structure of CCITT IN standards 16

4.2.4 Capability Set 1 17

4.2.5 IN CS1 Services 18

4.2.6 CCITT goals and objectives for services 19

4.3 IN Conceptual Model 20

4.3.1 Physical Plane 21

4.3.2 Distributed Functional Plane 26

4.3.3 Global Functional Plane 30

4.3.4 Service Plane 35

4.4 The IN-structured network 38

4.4.1 SCE 38

4.4.2 The function of IN 39

4.4.3 IN Application Protocol 40

4.5 Personal Communications Services 41

4.6 Integration of TMN and IN 42

4.6.1 Comparison of IN planes to TMN planes 43

4.7 Globalizing the IN 44

4.8 Future IN Capability Sets 44

4.9 Current activities of IN 45

5. CHANGES IN BUSINESS 46

5.1 Technology and services 46

5.2 IN services 475.2.1 Benefits of IN 47

5.2.2 Cost structure 48

5.2.3 Service portfolio 49

5.3 Evolution of IN capabilities in Telecom Finland 50

5.3.1 Pre-IN 50


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5.3.2 Centralized IN 50

5.3.3 Special services 50

6. BROADBAND INTELLIGENCE AND MEDIA 51

6.1 Broadband networks 51

6.1.1 B-ISDN 51

6.1.2 ATM networks 53

6.2 Applications for the broadband networks 55

6.3 Broadband IN 56

6.4 Telecom Finland B-IN project 57

6.4.1 The hardware configuration 57

6.4.2 TMN and B-IN 58

7. REFERENCES 60


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ABBREVIATIONS

AAB Automatic Alternative Billing

ABD Abbreviated Dialling

AC Application Context

ACB Automatic Call Back

ACC Account Card Calling

AD Adjunct

AOD Audio On Demand

AP Application Process

ASE Application Service Element

ASN.1 Abstract Syntax Notation One

ATM Asynchronous Transfer Mode

ATT AttendantAUC 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 FunctionCCBS 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


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CD Call Distribution

CD Compact Disk

CD-ROM Compact Disk-Read Only Memory

CF 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 AnnouncementCRD Call Rerouting Distribution

CRG Customized Ringing

CS Capability Set

CS1 Capability Set 1

CT2 Cordless Telephone 2

CUG Closed User Group

CW Call Waiting

DC 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

EC European Community

EF Elementary FunctionEIR Equipment Identification Register

ERMES European Radio Message System

ETSI European Telecommunications Standards Institute

FC Functional Component

FE Functional Entity

FEA Functional Entity Action


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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 RegisterHP Hewlett Packard

IN Intelligent Network

INA Intelligent Network Architecture

INAP IN Application Protocol

INCM Intelligent Network Conceptual Model

IP Intelligent Peripheral

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-ConferenceMPEG 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


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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 PartONC 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

PCS Personal Communications Services

PDH Plesiochronous Digital Hierarchy

PE Physical Entity

PIN Personal Identification Number

PLMN Public Land Mobile Network

PN Personal Numbering

PNP Private Numbering Plan

POI Point Of Initiation

POR Point Of Return

PRI Primary Rate InterfacePRM Premium Rate

PRMC Premium Charging

PSTN Public Switched Telecommunications Network

PTN Personal Telecommunications Number

PVC Permanent Virtual Channel

QOS Quality of Service


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QUE Call Queueing

RACE Research and technology development in Advanced Communications

technologies in Europe

RBOC Regional Bell Operating Company

REVC Reverse Charging

rN 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 PartSCE Service Creation Environment

SCEF Service Creation Environment Function

SCF Service Control Function

SCF Selective Call Forward on Busy/Dont Answer

SCP Service Control Point

SDF Service Data Function

SDH Synchronous Digital Hierarchy

SEAL Simple and Efficient Adaptation Layer

SEC Security Screening

SF Service Feature

SIB Service-Independent building Block

SIG Special Interest Group

SLP Service Logic Program

SMS Service Management System

SP Service Plane

SPC Stored Program Control

SPL Split ChargingSRF Specialized Resource Function

SS Service Subscriber

SS7 Signalling System no. 7

SSD Service Support Data

SSF Service Switching Function

SSN Subsystem Number


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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

TP Transact Processing system

TRA Call TransferU_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

UP User Part

UPT Universal Personal Telecommunications

VBR Variable Bit Rate

VC Virtual Circuit

VCC Virtual Channel Connection

VCI Virtual Channel Identifier

VLR Visitor Location Register

VOD Video On Demand

VOT Televoting

VP Virtual Path

VPI Virtual Path IdentifierVPN Virtual Private Network

WSF Work Station Function


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IN - Tutorial for the Proceedings of the First Winter School on Intelligent Networks in Helsinki at Telecom Finland

Lappeenranta University of Technology & Telecom Finland Kim Molin, Olli Martikainen

25th February 1994

1

1. Preface

This paper is made for the participants of the

Proceedings of First Winter School on Intelligent

Networks to be held in Helsinki at Telecom Finland on

March 1994. This tutorial is done in cooperation with

Lappeenranta University of Technology and Telecom

Finland. This study is supposed to be a tutorial for the

Intelligent Networks (IN) that studies IN from user,

operator and software points of view. This tutorial gives

some history of the development of computers and

telecommunications networks towards more advanced

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

networks and architectures that add value to

conventional telecommunications networks are often

referred to as Intelligent Networks (IN). This guide

provides an explanation of IN concepts, standards and

technologies and gives some view concerning the subject

of the situation today. Also some changes in the area of

telecommunications business is concerned. Also some

forecasts to future developments of IN are provided. The

author of this tutorial apologies for the possible mistakes

that exist in this article and remarks that some critics

and notices are welcome concerning the subject.

Section 2. describes the history of telecommunications

and its development towards the future techniques. The

changes in the switching systems and some turning-

points in telecommunications are allthough the main

concern. The concept of Computer Controlled

Telecommunications is described in section 3. Section 3.

also includes signalling network history and

development, management networks for

telecommunications networks, and the need for more

advanced services. The Intelligent Network Architecture

(INA) is shown 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 affects of telecommunications networks

development to the changes in business are studied.

Some additional discussion of broadband networks and

broadband services in Intelligent Networks is provided

in section 6. This section also informs of a research

project running at Telecom Finland in 1994.


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25th February 1994

2

2. Introduction

2.1 Early computers and telecommunications

Since electronic machines got some kind of intelligence

it is almost fifty years ago. Since then, the development

of these machines towards computers has been rapid. In

1950s there were no data networks because of the

insufficient network technology and the use of them

would have been minimal. In those days, computers

acted as batch processors. The programming of them

was very difficult, because they needed paper tapes to

inform the computer of the function needed. These batch

processors work 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 was far too inefficient to use the

analogous telecommunications network that was

provided at that time. The computers in those days were

only used to scientifical calculations that needed no

other I/O operations than instruction and data read, and

a printout function of the calculations. So computers

were completely in local use in those days.

The next generation of computer technology was the

appearance of computers into real world use. They had

more intelligence than the computers just a decade

before. The first use of computers was in the process

industry where computers removed process control tasks

from humans in the 1960s. This meant that the I/Ooperations of the computers were more developed and

they could already communicate with other devices.

Later on, the process industry became heavily computer

controlled. It was also then when the first uses of

telecommunications networks became possible. This was

done by modems with signalling rates of about 300

bauds. In those days, the telecommunications networks

did not provide bit errorfree data transfer. Bit errors

appeared very often and it was then when transport

protocols at end systems and heavy link and network

protocols between the network nodes were developed to

minimize this unreliability problem.

Figure 0-1. Transaction processing system.

In 1970s Transaction Processing (TP) systems were

taken in use in the area of banking. These TPs locatedin the main office and worked like servers there. The

clients sended requests via the communication network

and the TP answered them with responses. (Figure )

TPs and communication networks have developed a lot

and this client-server model is still in use in banking. At

day time, computer systems work as transaction

processors, but at night as highly developed batch

processors. This is because they are incapable of serving

the requests (even thousands of requests per hour) that

might come from several offices simultaneously. Such

batch functions are for example the payment of salaries

every month. However, these computer systems need to


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25th February 1994

3

serve the realtime queries and give responses to

hundreds of locations worldwide.

2.2 Switching systems development

From 1870s to 1950s, the primary focus of swithing

system development was on producing better

technologies for permitting two people to engage in

voice communications over larger and larger distances

and to 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, to Stores Program

Control (SPC) switches. It is interesting to read 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 information, information about

how to provide the limited functions available at that

time, and implicit network information were all

contained in each switch. Benne93

In the 1950s, Direct Distance Dialing (DDD) began to

be deployed as a new service, but this was still a

continuation of the general focus on providing

telecommunications connections between fixed points

(usually two). Furthermore, the long development time

frames and the then-available technologies favored

producing this new service by slightly rearranging the

internal structure of the switching systems and

squeezing in the new capability. The end result was

that DDD moved considerable network-related data into

the local switches and also added new functions related

to the network connection capabilities into the local

switches. On many of the existing switches, this

involved adding specialized boxes to correctly

interpret the new dialed numbers and route them to the

correct places for proper DDD connectivity. To get some

idea of the technological problems associated only 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 services at this time

was the reduction in the cost of the connections so that

smaller groups of people with specialized needs were

entering the market and 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 good, clean and economical connections. Thus,

there was no driving need to reorganize the basic

structure of what existed; nor was there any real

guidance as to what kinds of services the customers

would be willing to purchase as a service marketing was

in its infancy. Benne93


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25th February 1994

4

During the 1960s and 1970s, the requests for

additional services began to grow, but the pace was

rather leisurely by todays standards since the

technology to support these new services was not readily

available on the general market. For example, the fax

technologies available were not very advanced and did

not produce sufficiently high-quality results to enable

people to change their basic methods of operation to

incorporate faxes into their work as they do today. Also,

the derivative technologies associated with the growth of

computers, personal computers, and microchip

technology had not reached a state where they were

demanding telecommunication services much beyond

classical interconnectivity services. However, the genesis

of the current service-driven climate occurred during

this period as the specialty groups began to experiment

with new ideas and request new services. Once again,

the pace was such that 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 bse for the newer services. During this period,

the efforts to put more and more new service capabilities

onto the switching systems resulted in a large expansion

of the types of information being placed on the switches,

e.g., variations of call models proliferated, more

network-related information was brought into the

switches, and data under the control of the end users

was moved onto the switches (speed calling lists, centrex

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

the programs to manipulate the data and ensure its

integrity also had to be moved onto the switches. This

resulted in the switches becoming very general data

control and usage systems as well as the connection-

producing systems they had traditionally been. Benne93

As we entered the 1980s, the technologies derived form

the computer and space industries began to be felt in the

general marketplace. 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. Another major factor driving toward more

specialized services was the breakup, in the United

States, of the Bell System and resulting competition,

where services were the factor that differentiated one

carrier form another. Furthermore, with diversiture, the

former local operating companies were permitted to

make instructions into one anothers traditional service

areas and, to do this effectively, they needed to have

something to offer that was not available from the local

service provider. All of these changes resulted in

customers being more aware of what technology provide

and demanding that the telecommunications industry

change to meet the new requirements for services.

Benne93

The 1990s 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 1980s, network development was

driven by the need to provide cheap, efficient

interconnections between fixed points. There was only

minor 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 interconnectioncapabilities and end-user services will be interchanged.

The demans for more and more specialized end-user

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


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25th February 1994

5

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 services.

In summary, the telecomunications industry, which has

been interconnection-driven, will, in the future, be

service-driven. Benne93 These facts will be discussed

more entirely later in this paper.

2.3 Turning-points in telecommunications

Several turning-points can be found in the history of

telecommunications technology (marked as circles in the

figure). (Error! Reference source not found.) 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 ratio. 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 data networks were developed especially for

corporative use. Second, CCITT (Concultative

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 1980s

radio signalling technology was advanced enough to

provide digital telephony service. The GSM (Global

System for Mobile communications) mobile phone

technology, introduced in 1992, is also suitable for low-

speed data transfer. The Intelligent Network is an

architecture ment 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

introduction of CCITTs SDH (Synchronous Digital

Hierarchy) technology the physical data transfer rates

increased remarkably. A 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) and broadband IN. These technologies

will be discussed more accurately later on.

Figure 0-2. The development of telecommunications.

2.3.1 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 like cordless

telephones (CT2 (Cordless Telephone 2) and DECT

( Digital European Cordless Telecommunications)),

mobile telecommunications systems (GSM and PCN)


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6

and radio message systems (ERMES (European Radio

Message System)). Hara93 (Figure )

UMTS is researched in RACE financed by EC

( European Community) and ETSIs group SGM5.

UMTS is an advanced systems concept which defines a

mobile communications system where a mobile phone

could be used at home, office and elsewhere. Hara93

UMTS is an open system which is based on TMN and

IN concepts. The system supports ISDN services and

could be at some degree compatible with B-ISDN. This

system is a very advanced telecommunications system

that supports global mobility and Intelligent Network

services and is not expected to be introduced before the

year 2000.

Figure 0-3. Evolution of mobile services and systems.


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25th February 1994

7

3. Computer Controlled

Telecommunications

3.1 CCITT Signalling System No. 7

The word signalling ment the transfer of analogous

signals in a network, for example in the analogous

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) Modar90, information needed for

distributed application processing (inter-process

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

management information.

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 inband (i.e. signalling information is

conveyed over the same channel that is used for speech)

Modar90; call set-up times are long (from about 10 to 20

s); limited information can be transferred resulting,

among other things, in restrictive network routing

capabilities.

With the introduction of electronic processors in

switching systems came the possibility of providing

Common Channel Signalling (CCS). This is an out-of-

band signalling method in which a common data

channel is used to convey signalling information related

to a number of trunks. Modar90 CCITT published this

new signalling protocol stack SS7 (Signalling System

No. 7) based on CCITT OSI (Open Systems

Interconnection) Reference Model (OSIRM) in 1980.

SS7 is fully digital and SS7 protocols correspond to the

first three layers of the OSIRM and includes also

protocols at the application layer. (Figure ) The

signalling network structure component of SS7 is the

Network Service Part (NSP), and it consists of the

Message Transfer Part (MTP) and the Signalling

Connection Control Part (SCCP). The upper layer part

of the SS7 protocol architecture consist the User Part

(UP).

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.

Lehti93


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25th February 1994

8

Figure 0-1. SS7 protocol architecture.

3.1.1 Network Services Part

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

it provides a connectionless message transfer system that

enables signalling information to be transferred across

the network to its desired destination. Functions are

included in MTP that allow system failures to occur in

the network without adversely affecting the transfer of

signalling information. So the overall purpose of MTP is

to provide a reliable transfer and delivery of signalling

information across the signalling network and to have

the ability to react and take necessary actions in

response to system and network failures to ensure that

reliable transfer is maintained. The first level of MTP

presents the signalling data link functions. A signalling

data link functon is a bidirectional transmission path for

signalling, consisting of two data channel operating

together in opposite directions at the same data rate. It

fully complies with the OSIs definition of the physical

layer. Level 2 of MTP presents the signalling link

functions. The signalling link functions correspond to

the OSIs data link layer. Together with a signalling

data link, the signalling link functions provide a

signalling link for the reliable transfer of signalling

messages between two directly connected signalling

points. The third level of MTP presents the signalling

network functions. They correspond to the lower half of

the OSIs network layer, and they provide the functions

and procedures for the transfer of messages between

signalling points, which are the nodes of the signalling

network. Modar90

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 OSIs 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 information used by SCCP to identify each of

the SCCP users at a node. Modar90

3.1.2 User Part

The User Part forms the most upper layer of the SS7protocol stack that use the services provided by the

lower layers SCCP and MTP. User Part functions are

ISDN-UP, TCAP (Transaction Capabilities Application

Part) and OMAP (Operations, Maintenance, and

Administration Part). The ISDN-UP is not discussed in

this paper. TCAP refers to the set of protocols and

functions used by a set of widely distributed applications

in a network to communicate with each other. TCAP

directly uses the service of SCCP. Essentially, TCAP

provides a set of tools in a connectionless environment

that can be used by an application at a node to invoke

execution of a procedure at another node and exchange

the results of such invocation. As such, it includes

protocols and services to perform remote operations. It is


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9

closely related to the OSI Remote Operations Service

Element (ROSE). The OMAP of the SS7 protocol stack

provides the applications protocols and procedures to

monitor, coordinate, and control all the network

resource that make communications based on SS7

possible. Modar90

3.1.3 Signalling network structure

Figure 0-2. CCITT SS7 network structure.

Signalling networks consist of signalling points and

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 level 3 is said to be a STP (Signalling

Transfer Point). Signalling points that are STPs can

also provide functions higher than level 3, such as SCCP

and other level 4 functions like ISDN-UP. When

signalling point 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, STPs (stand-alone and

integrated), and signalling points with level 4 protocol

functionality can be combined in many different ways to

form a signalling network. The SS7 Network Services

Part protocol is specified independent of the underlying

signalling network 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 redundancies for the signalling links,

which have unavailabilities measured in many hours per

year. In most cases the STPs must also have backups.

Modar90

The worldwide signalling network is intended to be

structured into two functionally independent levels: the

national and international levels. This allows numbering

plans network management of the international and the

different national network to be independent of oneanother. A signalling point can be a national signalling

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

serves both, it is identified by a specific signalling point

code in each of the signalling networks. Modar90

3.2 Telecommunications Management Network

Telecommunications Management Network (TMN) is a

generic, management-oriented architecture, intended to

be used for all kinds of management services. Appel93 It

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

According to the concept it intends to meet several

purposes: several network and devices, digital and

analogic transmission systems, circuit- and packet

switched data networks, public exchanges and PABXs

(Private Access Branch Exchange).

TMN is intended to support different management based

areas. These five functional areas are:

Performance management

fault management


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configuration management

accounting management

security management

The functionality of TMN consists of the following

subjects: M3010

the ability to exchange management information

across the boundary between the telecommunications

environment and the TMN environment.

the ability to convert management information

from one format to another so that management

information flowing within the TMN environment

has a consistent nature

the ability to transfer management information

between locations within the TMN environment

the ability to analyse and react appropriately to

management information

the ability to manipulate management information

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

management information user

the ability to deliver management information to

the management information user and to present it

with the appropriate representation

the abilty to ensure secure access to management

information by authorized management information

users

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:

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 areto 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 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 thefunctionalities and information modelling entities

related to the TMN man-machine communications

between the management system and the human

operator. Appel93

Between the function blocks NEFs, OSFs and WSFs

there are different kind of reference points: Q-, F- and

X-type. The Q-type reference point is between OSFs of

contiguous layers or between the OSF and the NEF; the

F-type reference point is between the WSF and the OSF;

and the X-type reference points are between OSFs

belonging to different domains.


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Figure 0-3. TMN Operations Systems functional

hierarchy. Appel93

3.2.2 Informational architecture

TMN informational architecture is based on Object-

Oriented (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). M3010

Management of a telecommunications environment is an

information processing application. Because the

environment being manages is distributed, network

management is a disributed application. This involves

the exchange of management information between

management processes for the purpose of monitoring

and controlling the various physical and logical

networking resources (switching and trasmission

resources). M3010

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 also reflect to the manager a view of

these objects and emit notifications reflecting the

behaviour of these objects.

Figure 0-4. Interaction between Manager, Agent and

managed objects.

In TMN the manager uses polling method to get the

information from the agents. The agents store the

statictics information in their databases that are called

MIBs ( Management Information Base). A MIB is a

conceptual database structure. It represents the set of

managed objects within a managed system. The

structure of the MIB is often showed in the form of a

tree. This tree is called a Management Information Tree

(MIT). (Figure 0-5) The tree is organized in a

hierarchical way. At the upper parts of the tree resides

the most meaning attributes and they are specified more

entirely with the lower layer attributes.


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Figure 0-5. Management Information Tree.

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.

3.3 The need for IN

In the past few years the development of

telecommunications networks has been rapid. Thetelecommunications network technique before was

controlled mainly by operators. The desire to share data

and distribute application processing among network

elements, the need for standard interfaces between them

Garra93 and user demands for more sophisticated

telecommunications services has changed the

controlling of network elements notably. The

telecommunications network elements today are

controlled either by or interface with software.

The development of IN architecture was initiated by

Bellcore in USA almost ten years ago in order to help

the Regional Bell Operating Companies to become more

competitive in 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

database in a Service Control Point (SCP) for

controlling and managing the various network services.

Lauta93

The network architectures, so far, have developed

almost independently of each other. This point of view,

of course, causes the network operators and service

providers to provide independently implemented service

to customers. The basic idea of IN has been that it

integrates the services provided by the

telecommunications networks today and thus, providing

subscribers with more advanced services. So, the IN actsas a distributing and centralizing unit of the

telecommunications services provided today. This way,

it is possible to introduce more advanced services

rapidly and cost effectively.

3.3.1 Mobility and users identification

Before, the users had an identification that was based

exactly on the place where their access points to thetelecommunications network resided. The users access

points were differentiated from each other with the

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

telecommunication systems for example the telephone

number that did not support any mobility at all.

According to the physical location there are three

identification codes: N_IDs, S_IDs (Service ID) and

U_IDs (User ID). (Figure 0-6) S_ID defines the service

that is used by the user and U_ID defines the exact user.

With these acronyms can be described that before the

relation between user and network IDs was like U_ID

N_ID.


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13

In the future there can exist several other relations too.

For example, the mobility of users and services. The

user can move from N_ID to another and use a service

that could be either distributed throughout the

telecommunications network or serve the user as a

mobile service. Also from different U_IDs can be

produced groups where the telecommunications network

is used as a private network inside the whole

telecommunications system. As a little more advanced

telecommunications system, for example, GSM uses for

mobility the relation that an U_ID describes a virtual

channel ID that the GSM network manages. The

Intelligent Network differentiates the user, network and

service from each other. This point of description can

manage mobility from each of its components and even

of different Intelligent Networks when IN uses services

from other INs. So, these are the main reasons for the

development of an IN.

Figure 0-6. Different relations between identifications.


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4. Intelligent Network Architecture

4.1 Overview of IN

The IN is a telecommunications network services

control architecture. In February 1985, a Regional Bell

Operating Company (RBOC) submitted a Request For

Information (RFI) for a Feature Node concept with the

following objectives: Ambro89

Support the rapid introduction of new

services in the network

Help establish equipment and interfacestandards to give the RBOCs the widest

possible choice of vendor products

Create opportunities for non-RBOC

service vendors to offer services that

stimulate network usage

As with the past telecommunications technology, it was

not desirable to introduce short term services, because of

the long implementation and development period. Now,

with IN technology it is possible to introduce new

services rapidly without affecting the available services.

IN defines a great set of standards that describe the

interfaces between different network control points.

With only specifying the interfaces IN makes it possible

for vendor systems to provide with different products

and ,of course, for operators to use any of these products

in their network configuration. IN includes also

capabilities for other than operators to introduce new

services into the telecommunications network. This will

whole a lot change the structure of telecommunications

business which is the main concern in the section 5. of

this paper.

The INs main advantage is the ability to orchestrate

exchange service execution from a small set of

Intelligent Network nodes known as Service Control

Points (SCP). SCPs are connected to the network

exchanges (known as Service Switching Points) via a

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 0-1) The SSPs detect when

the SCP should handle a service. The SSP forwards astandardized SS7 (TCAP) message containing relevant

service information. Via the TCAP message, the service

control logic in the SCP directs the SSPs to perform the

individual functions that collectively constitute the

service (such as connecting a subscriber number or an

announcement machine). Ambro89

The INs long term goal is the ability to introduce new

services, or change existing services quickly, without

having to adapt SSP software (only parameters or

trigger updates). The adaptation will be confined to the

SCP where parameters or stimuli are updated. This goal

will be achieved at first in two stages: IN/1 and IN/2.

Ambro89 IN/1 will be the first implementations of IN at

the beginning of 1990s and IN/2 will be introduced

perhaps in 1995 because of the delays in the other areas

of telecommunications technology. That is why the

plans have been to introduce stage IN/1+ before the true

IN/2 implementation to serve as a bridge between IN/1

and IN/2.


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

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

Green Number Service (GNS) with which a subscriber

can call a number free of charge. The SSPs contain

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

the SSP to send a message to an SCP in order to getinformation about the destination to which the call

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

significant changes in the SSPs to accomodate new

services.

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. There will propably be

one or more interim stages between IN/1 and IN/2, for

example IN/1+ where the SSP provides increasing

flexibility in accomodating rapid service creation.

. Stage 2: IN/2

Figure 0-1. Intelligent Network overview. Homa92

An Intelligent Network is able to separate the

specification, creation, and control of telephony services

from physical switching networks. The key benefit of

this capability is that exchange carriers will be able to

rapidly engineer new revenue-producing services, in

response to market opportunities, without having to relyon lenghty cycles for implementing them entirely on

switching fabric. Ultimately, service creation, or at least

service customization, can be extended to subscribers.

Homa92


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4.2 IN standardation

4.2.1 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

4.2.1.1 ETSI

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

standards for the European environment

to define European standards in areas where

quick response is required for technical

development

4.2.1.2 CCITT

Work on international standards for IN began at CCITT

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

standardation. CCITT expects that the specification and

deployment of IN will continue over a number of study

periods. CCITT name has changed to ITU

(International Telecommunications Union) and there the

Special Interest Group (SIG) is I (ITU-I). Its approach to

the development of IN standards assumes that it isnecessary to start with a minimum set of criteria which

are sufficiently open ended that they can evolve to meet

the needs of the long-term concept as this becomes a

practical reality. Roger90

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.

4.2.2 Phased standardation

To meet the goals and objectives, CCITT has embarked

on a phased standardation process toward the target IN

architecture. CCITT works on defining a set of

capabilities for each phase and simultaneously on

evolving the view of the target INA. (Figure 0-2) The IN

capabilities are called Capability Sets (CS). The

Capability Sets involve service creation, management

and interaction and also network management, service

processing and network internetworking. These CSs are

backwards-compatible to the previous CSs so the

standardation and implementation of the services can be

progressed through phases. Garra93

Figure 0-2. Phased standardation of IN.


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4.2.3 Structure of CCITT 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 Csxrecommendation part y will be numbered also

systematically such as 12xy. (Table 0-1) So, the

principles introduction for IN CS2 will be

recommendation number Q.1220.

00 - General

10 - CS1 1 - Principles Introduction

20 - CS2 2 - Service Plane (not included forCS1)

30 - CS3 3 - Global Functional Plane

40 - CS4 4 - Distributed Functional Plane

50 - CS5 5 - Physical Plane

60 - CS6 6 - For future use

70 - CS7 7 - For future use

80 - CS8 8 - Interface Recommendations

90 -Vocabulary

9 - Intelligent Network UsersGuide

Table 0-1. IN recommendations structure.

4.2.4 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.120x -series. (Table 0-2)

CCITTs and ETSIs standards do not differ from each

other in any way.

CCITT Study Group XI, Working Party XI/4 includes

representatives from most of the important

telecommunications network operators and equipment

vendors in the world. Study Group XVIII also is

involved in the initial set of IN standards, and is sharing

responsibility for the Introductory Recommendations. At

these meetings, there is an obvious willingness to

strongly focus on achieving a realistic initial set of IN

capability, which is both technically implementable and

commercially deployable.Duran92

New

RecommendationQ.1200

Q-Series Intelligent Network

Recommendations Structure

Draft


Principles of Intelligent Network

Architecture

Draft


Intelligent Network - Service

Plane Architecture

DraftRecommendation

Q.1203

Intelligent Network - GlobalFunctional Plane Architecture

NewRecommendationQ.1204

Intelligent Network - DistributedFunctional Plane Architecture

New


Intelligent Network - Physical

Plane Architecture

New


Intelligent Network - Application

Protocol General Aspects

NewRecommendation

Q.1211

Intelligent Network -Introduction to Intelligent

Network Capability Set 1

NewRecommendation

Q.1213

Intelligent Network - GlobalFunctional Plane for CS1

NewRecommendation

Q.1214

Intelligent Network - DistributedFunctional Plane for CS1

NewRecommendationQ.1215

Intelligent Network - PhysicalPlane for CS1

New


Intelligent Network - Intelligent

Network Interface Specifications


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NewRecommendations

Q.1219

Intelligent Network Users guidefor Capability Set 1

Table 0-2. IN CS1 recommendations.

In defining IN CS1, CCITT applied the INCM

( Intelligent Network Conceptual Model) using bothbottom-up and top-down approaches. The former

approach focused on modelling the capabilities of

existing networks in terms of functional and physical

architectures that could evolve the target IN

architecture, given CCITTs objective of evolving IN

from existing networks. The latter approach was service-

driven and it focused on identifying a set of IN CS1

services and Service Features. Then driving these down

through the INCM in order to identify the set of service-

independent capabilities for IN CS1, evolvable to the

target set of IN capabilities, and verify that this set could

be supported by the functional and physical architectures

defined via the bottom-up approach. Garra93

IN CS1 defines capabilities of direct use to both

manufactures and network operators in support of

circuit-switched voice/data services either defined or in

the process of being defined by CCITT. The primary

characteristic of the target set of IN CS1 services is that

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

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

service characteristic to limit the operational,

implementation, and control complexity for IN CS1.

Even with this limitation, it may be expected that

equipment suppliers will support interworking of IN

CS1 capabilities with existing switch-based services,

including more complex services such as those that

apply during the active phase of a call. For example, IN

CS1 routing, charging, and user interaction capabilities

may be used to 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 will mean

open interfaces between the SSP (Service Switching

Point) and SCP (Service Control Point), thus putting

into effect one of the most important goals of the IN,

namely vendor independence. Lauta93

4.2.5 IN CS1 Services

Allthough, by nature, the IN is a service independent

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

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 0-

3) and service features. A service is a stand-alone

commercial offering, characterized by one or more core

Service Features, and can be optionally enhanced by

other Service Features. A Service Feature is a specific

aspect of 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 serviceor an optional part offered as an enhancement to a

service. Q1211 The service composition and Service

Features will be discussed more precisely later on.


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Automatic AlternativeBilling (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/Dont Answer (SCF)

Call Forwarding (CF) Split Charging (SPL)

* Completion of Call toBusy Subsrciber (CCBS)

Televoting (VOT)

* Conference Calling(CON)

Terminating CallScreening (TCS)

Call Rerouting

Distribution (CRD)

User-Defined Routing

(UDR)

Destination CallRouting (DCR)

Universal Access Number(UAN)

Follow-Me-Diversion

(FMD)

Universal Personal

Telecommunications(UPT)

Freephone (FPH) Virtual Private Network (VPN)

Note: The service indicated with a * may only be

partially supported in CS1, because they require

capabilities beyond those of type A services.

Table 0-3. Target set of IN CS1 services.

4.2.6 CCITT goals and objectives for services

CCITT has defined goals and objectives for IN. The goal

of work for IN is to define a new architectural concept

that meets the needs of telecommunication service

providers to rapidly, cost effectively, and differentiallysatisfy their existing and potential market needs for

services, and to improve the quality and reduce the cost

of network service operations and management. Garra93

IN should be applicable to all telecommunications

networks, such as Public Switched telecommunications

Networks (PSTN), including Integrated Services Digital

Networks (ISDN), both narrowband and broadband,

packet-switched public data networks, and mobile

networks. Allthough, IN CS1 enables only the use of

PSTN, PLMN (Public Land Mobile Network) and ISDN.

IN should enable service providers to define their own

services, independent of service-specific developments

by equipment suppliers.

CS1 is intended to address services with high

commercial value, focusing at addressing flexible

routing, charging, and user interaction services. The list

of benchmark services and features will be listed later

on. Standardization of these services, however, is not

CCITTs role. An important characteristic is that theservices will be technologically feasible and

understandable, but do not significantly impact existing

deployed technology. In this context, services have been

categorized by CCITT as follows: Duran92

All type A services are invoked on behalf of and

directly affect a single user. Most type A services

can be invoked only during call setup of tear down

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

ended (no requirements for representing end-to-

end messaging or control), single point-of-control

(no requirement fro representing interaction points

between multiple service logic programs), and

single-bearer capability (one media profile). Type

A services may be used in conjunction with other

services, switch-based or not, of any type, to form

a more complete service package.


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Type B services can be invoked at any point

during the call. These services may be invoked on

behalf of and directly impact one or more users.

Feature interaction and arbitration, and topology

manipulation are capabilities that need to be

addressed to deploy these services. Note that it ispossible to use type A capabilities to enhance some

existing type B services.

The services addressed by CS1 fall under type A

services. The type A category lead to a series of

advantages in the context of CS1 standardization. First,

they represent a wide range of services of proven value.

Second, these services depend on well-understood

control relationships between network components and

this represents an 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 manufacturer. Duran92

4.3 IN Conceptual Model

The IN conceptual model is defined in the CCITT Draft

Recommendation Q.1201. The conceptual model is

divided into four planes and it forms the basis for the

standardation work. (Figure 0-3) 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: Q1215

service implementation independence

network implementation independence

vendor and technology independence

Figure 0-3. IN Conceptual Model. Draft91


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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 physicalentities (PE), in a network, and interfaces between these

Physical Entities. (Figure 0-4)

One or more Functional Entities from the Distributed

Functonal Plane may be realized in a Physical Entity on

the physical plane, and one or more relationships from

the Distributed Functional Plane may map into an

interface on the physical plane. The physical plane

architecture describes how functional architecture map

into Physical Entities and interfaces. Garra93 Also the

requirement for physical plane architecture is that

vendors must be able to develop Physical Entities based

on the mapping of Functional Entities and the standard

interfaces. Q1215

Figure 0-4. IN Physical Plane Architecture.

4.3.1.1 Physical Entities

The CCITT recommendation Q.1215 defines the

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

interfaces between PEs and which IN functionalities areincluded into them from the Distributed Functional

Plane and which of them are just optional entities.


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4.3.1.1.1 SSP

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

telecommunications network that acts like a PABX. To

make IN capabilities available to all types of access

arrangements, we must develop service management

independently of the access arrangements. Thisseparation 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

contains a Call Control Function, a Service Switching

Function, and, if the SSP is a local exchange, a Call

Control Agent Function. It also may optionally contain

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

provide IN services to users connected to subtending

Network Access Points. Q1215

The SSP is provided by the traditional switch

manufacturers. These switches are programmable and

they can be implemented in multipurpose computers.

The basic function of SSP is that the software in

switches separates basic call control from the service

control of IN.

4.3.1.1.2 NAP

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

ubiquitous deployment of IN services. This NAP cannot

communicate with an SCF, but it has the ability to

determine when IN processing is required. It must send

calls requiring IN processing to an SSP. Q1215

4.3.1.1.3 SCP

The SCP contains the Service Logic Porgrams (SLP)

and data that are used to provide IN services. 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. Functionally, an SCP contains a Service Control

Function and a Service Data Function. The SCF can

access data in an SDP either directly or 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. Q1215

The SCP comprises the SCP node, the SCP platform,

and applications. The node performs functions commonto applications, or independent of any application; it

provides all functions for handling service-related,

administrative, and network messages. These functions

include message discrimination, distribution, routing,

and network management and testing. For example,

when the SCP node receives a service-related message,

it distributes the incoming message to the proper

application. In turn, the application issues a response

message to the node, which routes it to the appropriate

network elements. Ambro89

The SCP node gathers data on all incoming and

outgoing messages to assist in network administration

and cost allocation. This data is collected at the node,


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and transmitted to an administrative system for

processing. Ambro89

The SCP node also measures the frequency of SCP

hardware and software failures, resource usage, overload

counts, and so on. It provides information needed to

perform maintenance procedures, thus minimizing the

impact of failures on system performance. The node may

take action to prevent and correct the overload at the

node or at a particular application. Ambro89

4.3.1.1.4 AD

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. Q1215 An Adjunct may be connected to more than

one SSP and an SSP may be connected to several

Adjuncts.

4.3.1.1.5 IP

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 a user and thenetwork. 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. Q1215

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 Adjunct can also request the SSP to connect a user to

a resource located in an IP that is connected to another

SSP. Q1215

4.3.1.1.6 SN

The Service Node can control IN services and engage in

flexible information interactions with users. The SN

communicates directly with one or more SSPs, ech with

a point-to-point signalling and transport connection.

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

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

SCF within the SN, and is not accessible by external

SCFs. Q1215

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 amanner 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 SSP. Q1215

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


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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 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. Q1215

4.3.1.1.8 SDP

The SDP contains the customer and network data which

is accessed during the execution of a service.

Functionally, the SDP contains an SDF. Q1215 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. Q1205

4.3.1.1.9 SMP

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, and network data

collection. Functionally, the SMP contains the Service

Management Function and, optionally, the Service

Management Access Function and the Service Creation

Environment Function. The SMP can access all other

Physical Entities. Q1205

A Service Management System is the operations system

through which network operator and service subscriber

personnel manage SCPs and related service applications

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

may be associated with the IN; the network operating

company may want a separate SMS for each IN service

or a single SMS for several IN services. Ambro89

Physically, the SMS resides in a multipurpose computer.

Processing power and database size requirements

normally govern the choice of a specific computer. The

SMS manages a private network consisting of switched

and leased line connected to a set of keyboard or display

terminals through which network operator and service

subscriber personnel gain interactive messages to the

system. Ambro89

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. Q1205

4.3.1.1.11 SMAP

The Service Management Access Point provides some

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. Q1205

4.3.1.2 Interfaces between PEs

In the Physical Plane Architecture several standardized

interfaces are stated. These interfaces are: SCP-SSP,

AD-SSP, IP-SSP, SN-SSP, SCP-IP, AD-IP, and SCP-

SDP.

Existing lower layer protocols are proposed for these

candidate interfaces to carry the application layer


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

the standardization effort for CS-1 is on the applications

layer protocols. At the application layer, the message

sent that the different interfaces carry should reflect the

same semantic content, even though the application

layer message may be encoded or formatted differently.

For example, the messages between the SSF in an SSP

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

the same information. The following sections give some

proposed protocols for use on these interfaces. Q1215

4.3.1.2.1 SCP-SSP interface

The proposed underlying protocols platform for the

interface between an SCP and an SSP is Transaction

Capabilities Application Part (TCAP) on Signalling

Connection Control Part (SCCP)/Message Transfer Part

(MTP) of SS7. Q1215 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.

4.3.1.2.2 AD-SSP interface

Th

in tutorial

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