Access and Traffic handling

Access and Traffic handling this is designed to provide the student with knowledge about the traffic handling in AXE. Different ways to access the AXE are also mentioned. The analyses that are performed in TCS subsystem in order to set up a call are also described.

8 ACCESS AND TRAFFIC HANDLING

This chapter is designed to provide the student with knowledgeabout the traffic handling in AXE Different ways to access theAXE are also mentioned

The analyses that are performed in TCS subsystem in order toset up a call are also described

A number of services are named both for PSTN and ISDNconnections and the differences between Bearer-, Tele- andsupplementary services are clarified

Intentionally Blank

The AXE supports a wide range of access products that can bedeployed by network operators to meet the service, bandwidthand mobility requirements of subscribers as economically andflexibly as possible

AXE can be accessed by subscribers who are (see Figure 8-1)

• Directly connected

• Connected via a remote subscriber switch (RSS)

• Connected via other Ericsson access products

• Connected to other access networks which support the V5interfaces

Applications supported by the local exchange

It brings the local business and residential subscribers thebenefits of speed and flexibility

RAS1000 Freeset

RSS

DIAmuX

MUX

RAS1000 Freeset

RSS

DIAmuX MUX

Figure 8-1 Accesses to AXE

Cu Copper FTTC Fiber to the curb MUX Multiplexer PABX Private automatic branch exchange RSM Remote subscriber multiplexer RSS Remote subscriber switch

The different accesses will be described more in detail inchapter 10

In the next part a short description of the different PSTN andISDN services follow

PSTN SERVICES

Introduction

The rapid development of telecommunications and thederegulation of the market have lead to increased competitionfor network operators

Although other applications are growing, telephony servicesoffered by the PSTN continue to be a major application

Network operators can maximize their revenue from the PSTN

by offering a broad range of services and stimulating use of thenetwork

The AXE supports a full range of PSTN services including:

• Basic services

• Call management services

• Business support services

• Custom local area signaling services (CLASS)

The services may not be used that very often, but when needed they have a high value for the subscriber.

Basic Services provides the facilities in a local exchange that ensure different supplementary services work together.

PSTN call management services

These services provide the operating company with revenueopportunities by offering the end user increased control of andcomfort in his telephone usage Services included are:

• Remote control of supplementary services, which enables

end-users to control remotely a service when they are awayfrom their home or office

• Distinctive alerting service, which allows four directory

numbers, each with its own distinctive ringing, to beassigned to a single line

• Change of keyword, which enables end-users to choose and

change keywords if they have elected to use one to controlPSTN services

• Call barring services, which enable end-users to control

which types of outgoing calls, can be made

• Call forwarding services, which allows the end-users to

direct incoming calls to another location

• Three party service, which allows an end-user to consult

third parties and add teleconferences without having to makeseveral separate calls

• Three party call with call transfer, which enables end-users

to transfer a call to a third customer and then leave the call

• Call waiting service, which informs an end-user, while

he/she is having a conversation on the telephone, thatanother call is waiting

• General deactivation service, which enables an end-user to

deactivate all currently active subscriber services

• Automatic meet me service, which offers end-users the

possibility to set up and participate in conference callswithout the aid of an operator

PSTN business support services

These services can be very valuable for especially businesscustomers as they can increase their service level The servicesgenerate revenues for the network operator and also increase theutilization of the network Services included are:

• Changed number announcement service, which is intended

for end-users who have moved or changed their telephonenumber All incoming calls are redirected to a variableannouncement machine

• Queue service, which enables callers receiving a busy signal

to be placed in a queue

Custom local area signaling services (CLASS)

AXE offers a growing range of caller identification services,known as custom local area signaling services (CLASS)

These services provide the basic telephony subscribers with arange of individual functions, features and information that helpthem get more out of their telephones

The services provided with CLASS create subscribersatisfaction and extra revenue from conventional telephonyservices

CLASS services can be charged to subscribers on the basis of aregular subscription or a fee each time a particular service isused

Because CLASS services are based on information from thecalling party, a switching and transport network, which supportsthe necessary signaling between exchanges, is required

Some CLASS services can be accessed through standard phones However a display capability is needed to fully exploitthe services

tele-Dual tone multi frequency (DTMF) or frequency shift keying(FSK) signaling is required to transmit information about thecalling subscriber to the called subscriber’s system terminal

CLASS services include:

• Completion of calls to busy subscriber, which enables calls

to a busy line to be completed when the line becomes free

• Completion of calls on no reply, where a call receives no

answer this service automatically monitors the calledsubscriber line when activated

• Malicious call identification, which enables a customer to

request a network operator to identify malicious, nuisance orobscene callers

• Calling line identification presentation (CLIP), which

enables the identity of a caller to be displayed on the calledparty’s telephone

MFC Multi frequency compelled TUP Telephony user part

• Calling line identification restriction (CLIR), which enables

an end-user to prevent the presentation of his/her number to

a called party

• Call answering service/message waiting indication enables

end-users to have incoming calls directed to a voice mailbox

AXE

Voice mail box

Figure 8-3 Call answering service/message waiting indication

CAS Call answering service DTMF Dual tone multi frequency FSK Frequency shift keying ISUP ISDN user part

MWI Message waiting indication TCAP Transaction capabilities application part TUP Telephony user part

TRAFFIC HANDLING

GENERAL

With the introduction of the AM concept in AXE system, thestructure has been changed The Application Product containsthe XSS (eXisting Source System), RMP (Resource ModulePlatform) and the AMs (Application Modules)

The traffic control functions are then implemented in variousparts of the system

In XSS the Traffic Control Subsystem (TCS) controls andcoordinates all the main activities in the various parts of thesystem involved in call setup, supervision and disconnectionphases for both PSTN and old ISDN (non ISDN-E) subscribers

In the AM adapted application, the ISDN User ServiceApplication Module (IUSAM) and the Digital Access ServiceApplication Module (DASAM) handle some of the respectiveprocedures of the TCS for new ISDN subscribers, ISDN-E Theremaining procedures are performed within XSS (in TCS) orcoordinated by it

o/g data

i/c data

Seizure phase

- Storing of information

Setup phase

- Initial data -B-num analysis -Routing analysis -Subscriber analysis -End-of-selection analysis

Active phase

- End of call supervision analysis

Release phase

o/g data

i/c data

Seizure phase

- Storing of information

Setup phase

- Initial data -B-num analysis -Routing analysis -Subscriber analysis -End-of-selection analysis

Active phase

- End of call supervision analysis

Release phase

Figure 8-4 Survey of four phases in TCS

Functionality such as Reception of Call Information, Analysis ofCall Information, Seizure of Route/B-subscriber, ThroughConnection in the Group Switch, Sending of Call Information

and Call supervision, release and coordination of functions areall either performed within TCS or coordinated by TCS.

The traffic control subsystem handles a number of phases inorder to complete the call requests TCS is divided in a seizurephase, a setup phase, an active phase and a release phase

The first phase for a new call is the seizure phase where datafrom incoming side are stored in TCS TCS will be passive untilend of seizure is received

At end of seizure TCS will go in to the setup phase by startingthe below listed analyses and functions:

• Originating Telecommunication Service analysis

• Transmission Medium Requirement analysis

• Generation of call reference (In AM environment)

• Forced detailed billing

• Call event (seizure of register)

• Supervision of Register Holding Time

• Originating Closed User group

• Priority

• Network call identification/reference

• Flexible call processing (verification of DI)

• Flexible call processing (call type derivation)

• Equal access

If any of the analyses or functions detects that a special action isneeded it is done by generating an EOS-code and go directly tothe end of selection analysis

TRAFFIC CONTROL FEATURES

The TCS is capable of handling both PSTN and ISDN calls Itsupports, also, interworking with subscriber and Intelligent Net-work (IN) services as well as the group switch with more than64k MUPs

With the introduction of the Application Modularity (AM)concept and the ISDN-E realization, two implementations ofISDN are present:

“Old-ISDN”, implemented in the XSS

“ISDN-E”, implemented in a number of System Modules (SM)and Application Modules.

In this module, the term “ISDN call” will refer to Old-ISDN As

an integral part of the ISDN-E application, the eXisting SourceSystem (XSS) acts as a transit node, the interface being theDigital Junctor blocks (DJI/ DJO) in the Subscriber ControlSubsystem (SCS) To the XSS, the DJ interface appears as anincoming trunk interface

ANALYSIS FUNCTIONS IN TCS

During the seizure phase, data from incoming side will be stored

in TCS TCS remains passive during the seizure phase

The Active phase takes over after the setup phase and is ended

by a Release phase The Setup phase can also be ended by aRelease phase

For non ISDN signaling systems and access types the sameevents for controlling the Setup phase and the Active phaseexists

• Telecommunication service analysisTelecommunication (Tele and Bearer services) services arecommunication capabilities offered by a network

Telecommunication service analysis is a function, which, at callfrom an ISDN subscriber or an ISDN route (in case of a transitexchange), analyses a number of information elements

originating from the call setup message

Telecommunication service analysis is spontaneously activatedfor all originating and terminating ISDN calls

In other nodes the analysis can be optionally activated byspecification of a specific result during analysis of digits in thecalled party number

• B-number analysis and related analyses / functions

When the initial functions and analyses have been successfullyexecuted the B-number analysis will be started The main resultsfrom the B-number analysis are routing case, terminating orEOS-code that indicates the action to be taken for exampleconnection to an announcement machine If none of the resultsare derived from the B-number analysis a forced release of thecall will be initiated

• Route analysisThe result from the route analysis is normally a route, but also asubscriber number can be received from the route analysis.

When the result is a subscriber number, TCS continues with thesubscriber analysis When the route is found the new functionsand analyses are activated/trigged before outgoing route isseized

• Subscriber analysisWhen the B-number analysis has determined that the call isterminating a subscriber pointer (SC-pointer) will bedetermined If no subscriber is connected to the SC-pointer theanalysis will result in an EOS-code When the subscriber hasbeen determined certain functions have to be checked

• End of Selection analysisThe End of Selection analysis is normally invoked when specialactions or situations occur It is therefore possible to receiveEOS-codes from almost all the analyses and functions above,and from functions and services inside and outside of TCS

* Terminating ISDN case

ROUTE ANALYSIS

ANALYSIS TERMINATING

Teleservice /TMR

COMPAT.

CHECK

Local B-sub.

Outgoing Route

*

* TECA

ANALYSIS

OBA

* Terminating ISDN case

* Terminating ISDN case

ROUTE ANALYSIS

ANALYSIS TERMINATING

Teleservice /TMR

COMPAT.

CHECK

Local B-sub.

Outgoing Route

*

* TECA

ANALYSIS

OBA

Figure 8-5 Survey of Basic Analysis functions in TCS

• Active phaseThe active phase is a supervision of the subscribers andinvocation of services when requested by the subscribers

• ReleaseRelease in the setup phase will lead to an end of selectionanalysis (EOS-analysis).

• Basic Call SetupThe function of basic call setup (that means a call without anysubscriber services) is needed to setup calls from callingsubscribers and incoming trunk lines to subscribers andoutgoing trunk lines

A survey of the basic analysis functions which is needed for abasic call setup is shown in Figure 8-5

TELECOMMUNICATION SERVICE ANALYSIS

Telecommunication Services are communication capabilitiesoffered by a network The Telecommunication services aredivided by ITU-T (CCITT) into the two main types, BearerServices and Tele Services In this module, the terms BearerService and Tele Services will refer to Basic services

Bearer Services provide the means to transfer speech and datainformation between users without alteration of the messagecontent

Teleservices combine the transfer function with an informationprocessing function They employ bearer services to transportdata and, in addition provide a set of higher layer functions

Telephony is an example of a teleservice

Figure 8-6 Teleservice and Bearer service

At the end of the seizure phase and when the setup phase startsthe originating Telecommunication Service Analysis (TSA) and

Transmission Medium Requirement Analysis (TMR) are

performed in the block TECA

The telecommunications service analysis is performed for anoriginating call It is a function, which is used to analyze thereceived information and compile the parameters into a fewsimple service identifiers, which from a network point of viewrepresent a unique service description

Telecommunication Service Analysis yields aTelecommunication Service Code, TSC as a result This TSCcode is used by other analysis functions, for example inCharging analysis Each TSC code can be defined to identify aspecific service For example TSC=2 can be defined to representthe teleservice telephony

The Transmission Medium Requirement, TMR analysis is

performed for incoming trunk and originating PSTN calls Thisanalysis will define the transmission media that is required inorder to provide the specific service defined by the parameterTSC Besides the analysis in TECA block will also define theparameter WSIG, Wanted signaling, in order to define thesignaling that is required for the specific service described bythe parameter TSC

That means that the TECA block will be used in order toidentify the required service the transmission requirements inorder to provide the service and the required signaling

The result of the analysis in TECA block is sent to the RE,Register block that open a record and keep all the resultsregarding the specific call

The RE block also keep the number that is dialed the so-calledB-number (A-number is the number of the subscriber thatmakes the call and B-number is the number of the subscriberthat receives the call)

The next step should be to perform B-number analysis in order

to find out how to make the further connection via the exchange

to the right B-subscriber

Since the B-number table located in block DA could be quitebig it is essential to start the analysis at a point that should givethe fastest result In order to find the entry point in the B-number table we perform what we call pre-analysis