Digit Analysis Doc

TABLE OF CONTENTS

CHAPTER-1 INTTRODUCTION TO DIGIT ANALYSIS

1.1 Overview1.2 Digit analysis1.3 Advantage of digit analysis

CHAPTER-2 TECHNOLOGY REQUIREMENT SPECIFICATIONS2.1 Technology – GSM2.2 GSM architecture 2.2.1 Network and Switching Subsystems 2.2.2 Radio Subsystems 2.2.3 Network Management Subsystems2.3 GSM Traffic functions 2.3.1 Location Update 2.3.2 Hand Over2.4 GSM Signalling

CHAPTER-3 CIRCUIT SWITCHING CORE3.1Product

3.1.1 MSS product, Functional units and Functions3.2 Digit Analysis and Routing

3.2.1Network Architecture3.2.2 Type of calls3.2.3 Dialing pre-analysis3.2.4 Tree significance3.2.5 Area service analysis

3.2.5 Origin analysis3.2.6 End of selection analysis3.2.7 Call barring analysis2.4.9 Routing and charging analysis2.4.10 Creation of digit analysis2.4.11 Tree significance2.4.12 Digit analysis components2.4.13 summary of digit analysis

2.5 Project work2.5.1 Call flow in general step by step 2.5.2 Digit analysis outcome step by step, digit analysis component, routing info 2.5.3 Provisioning of Digit analysis component, routing info2.5.4 Unsuccessful call trace-practical and explanation

CHAPTER-4 CONCLUSIONAPPENDIX A

- CALL FLOW - CAPACITIES, MAX DESTNATION/SUB-DESTINATION, ROUTING, CGR, CIRCUITS, HUNTING METHODS

ABSTRACT

CS -CORE, which is called circuit-switch core, is the main core in telecom domain where switching of the calls between two subscribers is taking place. Please refer the diagram, it contains MSS(MOBILE SWITCHING SERVER-server) and MGW(MEDIA GATEWAY-CLIENT).

The current architecture is 3GPP (3rd generation project programming), which is a global standard for 3G- services and the release of the network is” Release 4”.

The MSS and MGW work as a server-client based model, i.e., MSS is a server, MGW is a client. Whatever MSS instructs, MGW will execute the job. As we know that in telecom, we have signalling, CALL-RELATED AND NON – CALL RELATED which is called control plane in Rel 4, and Traffic, which is called User plane in Rel 4. We are going to discuss call related signalling to SETUP A CALL, TO CONTINUE A CALL, TO DIS –CONTINUE A CALL and Traffic, which will carry VOICE or DATA.

MSS will have the following functions

- Signalling towards the subscriber

- Collecting dialled numbers

- Collecting charging data

- Hunting for a free circuit

- Making speech Path connections

- Signalling towards other exchanges

- Analysing and subscriber data

- Supervising the process running

- Collecting statistical dataAs part of the Digit analysis – project preparation, we need to cover the following items.

- 3G knowledge- Theory

- Rel 4 network architecture-Theory

- SS7 and signalling- Theory

- MSS product, functional units and interfaces-Theory

- Call flow- practical

- Digit analysis and Routing- Practical

- Commands to create digit analysis- PracticalAfter covering all the above said topics, Engineer can demonstrate what the digit analysis in-depth is. With the above said project, student will get 100% job alsoCS core engineer job is the hot job in telecom market. Without digit analysis, we can’t claim he is a cs core engineer. The concept of digit analysis is same “3GPP Rel 4” across all the vendors

like NSN, ERICSSON, HUWAII, ZTE, ALCATEL-LUCENT and etc. The sample of call flow is mentioned below.

CHAPTER-1

Introduction to Digit Analysis

1.1 Overview

Currently in India, we are going to deploy 3G telecom services over 2G telecom services.

Right now we are following 3GPP Rel 4 specifications. Cs core is the Domain in telecom where

switching of the call will take place between calling subscriber and called subscriber.

In Cs core domain, we have the following network elements

-Mobile switching server, which will work as server and will handle signalling for

call-setup/continuity of call/Dis-connect of call which comes under call-related signalling.

- Mobile gateway, which is a client, will handle traffic such as voice call and data.

1.2 Digit Analysis

As part of signalling setup, we will cover digit analysis, i.e., analysing digit-by-digit of called

subscriber under B-number table, resulting, getting the destination of the call and routing of the

traffic.

Digit analysis is the one of the main function of CS core, without digit analysis, we can’t claim

as a cs- core engineer. The concept is as per 3GPP Rel4 specification, which is same across all

the vendors i.e. NSN, ERICSSON, ALCATEL-LUCENT, HUWAEII, and ZTE.

1.3 Importance of Digit analysis

With this project, engineer student will get job straightaway as a CS-core engineer. Without

Digit analysis, we can’t claim you are a CS-core engineer, that much importance it has.

CHAPTER-2

Technology Requirement Specifications

2.1 Technology-GSM

1st Generation Mobile Systems

The 1st generation mobile communication systems often offered nationwide coverage. They

were called as Analog Mobile Phone Systems (AMPS) however; there were limitations in 1st

generation mobile systems. Most of them did not support roaming. Roaming is the ability to use

another operator’s network infrastructure. International roaming is the ability to go even to

another country and use the local operator’s infrastructure. This was not possible in 1G because

of different standards being followed by different operators in different countries, which were

not compatible to each other.

Most 1st generation mobile communication systems supported speech transmission

only, Data transmission, such as fax, internet services were not available in 1G network.

Supplementary services, such as number indication and call forwarding when busy, which were

well known from ISDN, were also not available.

Another limitation in 1st generation mobile systems was lack of security. In most of

these systems, transmission took place unprotected via the radio interface – as a consequence,

eavesdropping was possible.

Finally, as mobile communication market growth was immense, the radio interface

came out to be the main bottleneck in terms of capacity. Improved solutions were urgently

required by all service providers. Also, a need was felt to standardize the equipments and

technology. This led to inauguration of 2nd generation mobile communication systems, one of

which is GSM.

2nd Generation Mobile Systems

The second generation mobile systems are generally known as Global System for Mobile

(GSM). To overcome the drawbacks in 1G mobile system a better approach and much efficient

2G system was introduced. The standard settings for GSM were under European Technical

Standards Institute (ETSI). The main aim of GSM was to provide roaming facility for the

subscribers and to follow Integrated Services for Digital Network (ISDN) guidelines.

2.2 GSM ARCHITECTURE

In GSM architecture the subsystems are

Network and Switching Subsystems (NSS)

Radio Subsystem (RSS)

Network Management Subsystem (NMS)

2.2.1 NETWORK AND SWITCHING SUBSYSTEM (NSS)

The NSS manages the connectivity between wireless networks and public networks. NSS contains:

i) Mobile Services Switching Centre (MSC)ii)Home Location Register (HLR)

iii)Visitor Location Register (VLR)

MSC: The MSC acts as highly reliable ISDN switches. It establishes connections between BSCs and all other MSCs. A single MSC can manage many BSCs of a particular region. A typical gateway MSC is termed as GMSC and it has additional fixed networks like PSTN and ISDN.MSC is responsible for controlling calls in the mobile network. It identifies the origin and destination of calls (Mobile system or fixed telephone), as well as the type of call. It sets up, supervises and clears connections. It helps in initiating of paging. Paging is the process of locating a particular MS in case of a mobile terminated call.

HLR: The HLR is very important database used in GSM standard in the sense it consists of all user related information. It consists of Mobile Subscriber ISDN number, the related services and authentication key facilities. The information regarding subscribers is linked to it. HLR also involves itself in charging and accounting details of subscribers.

VLR: VLR is responsible for any visitors or new subscribers entering the network. Whenever a new mobile subscriber enters the local area then visitor location register has to take immediate action so that it copies all related information about that new user.

2.2.2 RADIO SUBSYSTEM (RSS)

In GSM architecture the RSS consists of two main parts: i) Mobile Station (MS)

ii) Base Station Subsystem (BSS)

MS: In GSM, the mobile phone is called Mobile Station (MS). The MS is a combination of terminal equipment and subscriber data. The terminal equipment as such is called ME (Mobile Equipment) and the subscriber's data is stored in a separate module called SIM (Subscriber Identity Module). Therefore, ME + SIM = MS.

Mobile Equipment (ME): The Mobile Equipment ME combines the tasks of many functional elements of the fixed GSM-PLMN network. ME uses the data stored on SIM and digitizes speech. Speech is then compressed and secured against losses by adding redundancy bits and interleaving processes. ME also encrypts speech to prevent interception and modulates it onto the Radio Frequency (RF). Finally, the signal is amplified and transmitted on wireless interface. In the opposite direction, the process runs inversely, beginning with reception of the RF.

MS represents the counterpart to BSC, MSC, HLR, VLR and EIR as regards to signaling. As a whole, ME and SIM cards are almost a complete GSM system as regards their functionality.

SIM: SIM is certainly the best known database used in GSM network. SIM is a small memory device mounted on a smart card and contains user specific information. The SIM card can be taken out of one ME and inserted into another. In GSM network, the SIM card identifies the user just like a traveler uses a passport to identify himself. The SIM card contains identification numbers of the users and a list of available networks. It also contains the tools needed for authentication, ciphering, subscriber keys and security algorithms.

Few important things contained in a SIM card are:

Identifiers

Card type

Serial number

List of subscribed services

Personal identity number (PIN)

Authentication Key (K)

PIN Unblocking Key (PUK)

International Mobile Subscriber Identity (IMSI) etc

Base Station Subsystem (BSS):

The Base Station Subsystem is responsible for managing the radio network, which is the wireless part of mobile networks. Typically, one MSC contains several BSSs. A BSS itself may cover a

considerably large geographical area consisting of many cells (a cell refers to an area covered by one or more frequency resources). The BSS contains the following elements:

• Elements:

– Base Station Controller (BSC), Base Transceiver Station (BTS), and Transcoder

and Rate Adaptation Unit (TRAU, TC)

• Functions:

– Radio path control, BTS and TC control, synchronisation with MSC

– Air and A interface signalling, connection establishment MS-NSS

– Mobility management, speech transcoding

– Collection of statistical data

Base Transceiver Station (BTS): BTS is the network element responsible for maintaining the Air interface and minimizing transmission problems (the air interface is very sensitive for disturbances). This task is accomplished with the help of some 120 parameters. These parameters define exactly what kind of BTS is in question and how MSs may "see" the network when moving in this BTS area.

Characteristics of cells such as types of handovers (when & why), paging organization, radio power level control, identification, GPRS etc are defined as BTS parameters in the BSC.

Functions of BTS are:

– Air interface signalling

– Ciphering

– Speech processing (channel coding, interleaving, and burst formatting)

– Generation of alarms and statistics

– Baseband/Radio frequency transformation

Base Station Controller: BSC is the central network element of the BSS and controls the radio network. It has several important tasks listed below.

– Connection establishment between MS and NSS

– Mobility management

– Statistical raw data collection

– Air- and A-interface signalling support

– BTS and TRAU Control

Transcoder and Submultiplexer (TCSM):

In the air interface (between MS and BTS), the media carrying the traffic is a radio frequency. To enable an efficient transmission of digital speech information over the air interface, digital speech signal is compressed. We must however also be able to communicate with and through the fixed network, where the speech compression format is different. Somewhere between the BTS and the fixed network, we therefore have to convert from one speech compression format to another, and this is where the Transcoder comes in.

For transmission over the air interface, speech signal is compressed by the mobile station to 13 kbit/s (Full Rate and Enhanced Full Rate), 5.6 kbit/s (Half Rate), or 12.2 kbit/s (Enhanced Full Rate). A more modern speech codec is the AMR (Adaptive Multirate Coding) which is more flexible since it produces speech with bit rates similar to older solutions but adapted to link conditions.

However, the standard bit rate for speech in the PSTN is 64 Kbits/s. The modulation technique is called "Pulse Code Modulation" (PCM). This requires the GSM network to perform bit rate adaptation of speech.

TRAU thus takes care of the change from one bit rate to another. If the TC is located as close as possible to MSC with standard PCM lines connecting the network elements, we can, in theory, multiplex four traffic channels in one PCM channel. This increases the efficiency of PCM lines

and thus lowers the costs for the operator. When we connect to the MSC, the multiplexed lines have to be de-multiplexed.

2.2.3 NETWORK MANAGEMENT SUBSYSTEM (NMS)

Network Management Subsystem (NMS) is the third subsystem of the GSM network in addition to Network Switching Subsystem (NSS) and Base Station Subsystem (BSS), which we have already discussed. The purpose of NMS is to monitor various functions and elements of the network. This subsystem can often be referred to as OSS as well.

The functions of NMS can be divided into three categories:

Fault management: The purpose of fault management is to ensure smooth operation

of network and rapid correction of any kind of problems detected. Fault management

provides network operator with information about the current status of alarm events

and maintains a history database of alarms. The alarms are stored in the NMS

database and this database can be searched according to criteria specified by the

network operator.

Configuration management: The purpose of configuration management is to

maintain up-to-date information about operation and configuration status of network

elements. Specific configuration functions include management of radio network,

software and hardware management of network elements, time synchronization, and

security operations.

Performance management: In performance management, NMS collects

measurement data from individual network elements and stores it in a database. On

the basis of this data, the network operator is able to compare the actual performance

of the network with planned performance and detect both good and bad performance

areas within the network.

These functions cover the whole of GSM network elements from the level of individual BTSs, up to MSCs and HLRs.

2.3 GSM TRAFFIC FUNCTIONS

Location Update and Handover are the traffic that takes before and during the call

2.3.1 Location Update

– Mobile Station monitors the information broadcast by the network.

– Mobile Station stores the current location area identity in the SIM card.

– Mobile Station continues to monitor the broadcast information.

– If the location area identity being broadcast by the network is other than the one

stored in the SIM, the Mobile Station starts the location update procedure.

2.3.2 HandOver

It is defined as handing the call to next BTS or BSC without dropping of the call.

Hand Over occurs due to two reasons

Handover due to traffic reasons

– When the capacity of a cell nears its maximum, mobile stations in the periphery

of the cell may be handed over to neighbouring cell with lower traffic load.

– The MSC starts the procedure.

Handover due to signal quality and strength

– When a mobile subscriber is moving during a call, he may travel from one cell to

another.

– Frequency resources of previous cells can not be used any more.

– The mobile station is handed over to the new cell.

– The BSC controlling the current cell makes the decision to perform a handover.

– There are four types of these handovers.

Types of Handovers:

1. Intra BTS – Intra BSC

2. Inter BTS - Intra BSC

3. Inter BTS – Inter BSC

4. Inter BTS – Inter BSC – Inter MSC

1. Intra BTS:

In Intra BTS, the call is handled to other cell site within the same BTS.

Decision Maker: BTS

2. Inter BTS-Intra BSC:

In this situation, the call is handled to other BTS but both are located in the same BSC.

Decision Maker: BSC

3. Inter BTS-Inter BSC:

In this case, the call is handled from one BSC to another BSC under same MSC. Here, the

neighboring list is in MSC, the neighboring list contains the neighboring cell site of BTS and that

BTS is present in which BSC under which MSC all the details is present in MSC. According to

that the call is handed to the next cell site, if not the call drops.

Decision Maker: MSC

Condition: Neighbor List

Mc Mc

When A subscriber makes a call to B subscriber, A is in β sector of BTS B under

BSC A. As A moves to next sector α to BTS A of BSC B, but it is in same MSC. In this case, the

neighboring list is present in MSC in order to avoid call drop. The list contains the neighboring

sectors, BTS and BSC details. When the call moves from A to B, the neighbor list contains β

sector of BTS B under BSC A to α sector of BTS A under BSC B. When the call is moving B to

A, the neighbor list contains α sector of BTS B under BSC B to β sector of BTS A under BSC A.

Based on the list the call is handled successfully to next cell site.

MSC

MGW A MGW B

BSC A BSC B

βα γ γ γ γ

αα α

β β β

AbisAbis Abis

Abis

Aint Aint

BTS A BTS B BTS A BTS B

A Subscriber

B subscriber

4. Inter BTS-Inter BSC- Inter MSC:

In this case, the call is handled from one BSC to another BSC and different MSC. Here, the

neighboring list is in both MSC, the neighboring list contains the neighboring cell site of BTS

and that BTS is present in which BSC under which MSC all the details is present in MSC.

According to that the call is handed to the next cell site, if not the call drops.

Decision Maker: Both MSCs

Condition: Neighbor List

When A subscriber makes a call to B subscriber, A is in β sector of BTS B under

BSC A. As A moves to next sector α to BTS A of BSC B and to MSC B. In this case, the

neighboring list is present in both MSC in order to avoid call drop. The list contains the

neighboring sectors, BTS and BSC details. When the call moves from A to B, the neighbor list

contains β sector of BTS B under BSC A to α sector of BTS A under BSC B. When the call is

MSC A

MGW A MGW B

BSC A BSC B

βα γ γ γ γ

αα α

β β β

AbisAbis Abis

Abis

Aint Aint

BTS A BTS B BTS A BTS B

A Subscriber

MSC BB subscriber

Mc Mc

moving B to A, the neighbor list contains α sector of BTS B under BSC B to β sector of BTS A

under BSC A.

2.5 GSM SIGNALING

– Set of standard messages

– Many ways of implementation

– Evolution of multiple systems

– Problems in compatibility

– Development of Channel Associated Signalling

– Good for low traffic only

– Bottleneck and waste of bandwidth

– Development of SS7

– High capacity

– Signalling in the absence of a call possible

CHAPTER-3

CIRCUIT-SWITCHING CORE

3.1 PRODUCT

The basic mechanical structure of the DX 200 i-series network elements,

including the MSCi, follows a standard hierarchy:

Cabinets

Cartridges

Plug-in units

Internal cables

1.CABINETS

Cabinets contains racks, shelfs and frames. Each shelf has a number of computer

units. The computer unit performs its operation based on its functions. All the computer units are

connected to each other and communication takes between them with the help of message bus.

2.Types of cartridges:

• cPCI cartridges

-> 1/3-shelf cartridge CC3C-A

-> 1/4-shelf cartridge CC4C-A

• non-cPCI cartridges

-> 1/3-shelf cartridge, comprising type SD3C-B

-> 1/4-shelf cartridge, comprising types SD4C-B and SW1C-B

-> 1/6-shelf cartridges, comprising types ET5C-B, CLAC-B and CLOC-B

3.PLUG-IN-UNITS

The total number of different plug-in unit types used in a single i-series network element is approximately 30.

• cPCI plug-in units

• non-cPCI plug-in units

MSC contains five units:

Signaling Units

Switching related Units

Database related Units

External Interface and data related Units

Other Units

1. Signaling Units

These units are responsible for signaling, all these units carry SS7 signaling

towards different network elements.

It contains the following units:

BSU

CCMU

CASU

PAU

LSU

2. Switch Related Units

These units are responsible for switch operations i.e., call establishment, mobility

management and all switch related operations.

It contains the following units:

Group Switch

Marker

Tone Generator Field Programmable

Conference Circuit

3. Database Related Units

These units perform the functions of charging, collects information that is necessary

for charging and maintains VLR databases.

It contains the following units:

VLRU

STU

CHU

4. External Interface and Data Related Units

These units are responsible for collecting all the units data and are responsible for

transferring the data to respective units when it is necessary.

It contains the following units:

OMU

BDCU

ECU

ET

5. Other Units

These are some other units

Central Memory

Clock and Synchronous Unit

Verbal Announcement Generator

Message Bus

3.2 DIGIT ANALYSIS AND ROUTING

Whenever the call is made, the call is routed to the destination based on the

following analysis.

3.2.1 NETWORK ARCHITECTURE

3.2.2 Type of Calls

There are two types of calls:

1. Mobile Originated Call

2. Trunk Originated Call

1. Mobile Originated Call

The call if it is originated from the Mobile Station but the destination may be to same

PLMN, different PLMN or PSTN. These are the call that comes under MOC.

2. Trunk Originated Call

If it is originated from PSTN or PABX server and the termination to different or same

PLMN or PSTN. As PABX server is used in offices for intercoms, if the call comes the call is

routed to corresponding location. All calls that are directly connected to local exchange called as

Trunk call.

In MOC calls, basically there are four types of calls

1. Normal Call:

If the call originated from the mobile station for voice purpose called as Normal Call.

2. Emergency Call:

If the originated for the case emergency services for example using the services of

hospital known as Emergency Call.

3. Service Call:

If the call originated for the public services such as police

4. Data Call:

From the Mobile if the services of internet are used that is data is sent in the form of

packets. Here Mobile acts as a Modem.

3.2.3 DIGIT ANALYSIS

These are the three types of analysis used in Digit Analysis

1. Pre-Analysis2. Main Analysis3. Call Barring Analysis

Digit Analysis is done in MSC, once the pre-analysis is done the call is forwarded to further analysis i.e., Main Analysis. In this analysis, the routing is done and also Call Detailed Record(CDR) opens in MSC and in order to route the call, the call is forwarded to next step called Call Barring Analysis. Once the incoming call i.e., A number is barred by B subscriber is checked and then the call is processed to further steps for HLR Enquiry and the call is routed successfully. If not call the call is rejected in MSC itself and is sent back.

Pre-Analysis Main Analysis Call Barring Analysis

3.2.4 PRE-ANALYSIS

1. Pre-Analysis: This is the first step to be done in Digit Analysis. The Pre-Analysis is used to check whether the call made is genuine or not.

Types of Pre-Analysis:

The main objective of Pre-Analysis is to check whether the call made is Normal, Emergency or Service call. There are two types of Pre-Analysis

i. Normal Pre-analysis

When the call made is Emergency or Service call that comes under as Normal Pre-Analysis. It takes it as a Normal Pre-Analysis.

ii. Default Pre-analysis

Normal call takes it as Default Pre-analysis

Initially when the call originates, its checks whether it is a Voice, Emergency or Service call. Once it checks the type of the call made and then it processed to further steps.

To identify a Service, Service group or Emergency call To send dialed digits modification instructions on how to remove or add dialed digits To analyse the nature of the dialed digits and change it to the “Characteristics of

Number” Identity local calls Recognise a certain dialing pattern from the MS in order to proceed routing based on

calling line identity(CLI) Recognise prefixes for CLI presentation

These are steps that processed in the Pre-Analysis and the call is handled to next step

This is the trace when the call passes through pre-analysis, how the digits to be removed and it is further processed to next

This is the trace for the default pre-analysis, for normal call

This is the trace of TOC

3.2.5 TREE ANALYSIS:

It is the analysis which it will select tree number according to the call. For every call

processing either it may be a MOC or MOT calls, each call flows through this analysis and

according to the situation of the call it selects the tree number.

Whenever a MOC is made it selects the tree no. as 2

For call forwarding tree no. is 20

For service call tree no. is 30

Whenever announcements has to be made it selects tree 48

For automatic call redirection is tree 49

Whenever the called subscriber is in roaming it selects tree 50

For TOC , tree no. is 70 for national and international

3.3.6 AREA SERVICE ANALYSIS:

In this analysis, if the call is Emergency or Service call, this call goes to Area

Service Analysis as it gets the data where the call is originated and the service area and zone

code. During the Location Update process, initially when the SIM is inserted in the Mobile, the

network sends the LAI and TMSI which is stored in SIM and always will have the update profile

of where the subscriber is and which MSC/VLR area is serving based on these values, the

network have the zone code and the service number.

If the call made is emergency call, the pre-analysis is done and the call is and routed is tree

analysis. As it is a MOC it selects the tree no. as 2 and it is routed to area service analysis for

further process.

In this analysis, it gets service number and zone code and the call is routed to

further analysis called digit analysis. This call is not allowed through call barring analysis, as it is

an emergency call it doesn’t process it directly routes to the destination.

3.3.7 ORIGIN ANALYSLIS:

This is the analysis used to charge the subscribers in different ways. In this analysis, based on the subscriber the charging is done. For example, if the subscriber is calling to toll free number they will not be charged. For ordinary subscriber, they will be charged according to it.

Examples:

Free phone- Test Phone Normal Way - Normal Subscriber Expensive – Priority Subscriber, Density area

So in origin analysis based on the calling subscriber and the time for the conversation taken will be charged.

This is the trace for the charging origin of MOC

This is the trace of charging origin of TOC

3.2.8 END OF SELECTION ANALYSIS:

3.2.9 MAIN ANALYSIS:

This is also called as Routing/Charging Analysis. The output of the digit analysis is to reach destination. The routing component of digit analysis uses a routing hierarchy to select which route to use for a call. The analysis is based on the call’s destination as determined by the dialed digits analysis or by time-controlled routing. There are five alternative sub-destinations available for routing, from which one is normally selected according to its selection order and availability.

The analysis is done in the following way:

1. Create Digit Analysis

2. Crate Digit Analysis Components

Destination

Sub-destination

Charging

3. Create External Route

4. Add circuits to circuit group

5. Create Circuit Group

When a subscriber is calling the call is provisioned in the following way:

1. Create Circuit Group

2. Add circuits to circuit group

3. Create External Route

4. Create Digit Analysis Components

Charging

Sub-destination

Destination

5. Create Digit Analysis

Capacity:

Destination

Max.65536

Max.65536

Sub-destination Max. 4096

Max. 2048

MSC/VLR m 2046percircuitgroup

Digit Analysis

Destination Destination

Sub-destination Sub-destination

Route Route

Circuit Group Circuit Group

Hunting Group Hunting Group

Circuit Circuit

A destination can be reached via five alternative sub-destinations.

Each sub-destination has one route, which is the entity from which the free circuit is

hunted.

Each route consists of a maximum of eight circuit groups, which are characterized by

different priorities.

Each circuit group can be divided into two hunting groups. One consisting of even-

numbered circuits and the other of odd-numbered circuits.

Free circuits can be hunted by one of the following optional methods:

- circulating (hunting continues from where it stopped last)

- Sequential (always begins from the same point)

- Longest-free circuit (circuit that has been free for longest period is selected)

- Shortest-free circuit (circuit that has been free for shortest period is selected)

3.2.10 CALL BARRING ANALYSIS

It is used to determine whether a call can be allowed to continue or not. The result of this analysis is based on the supplementary service barring classes. When barring is based on the supplementary service, the type of the dialed digits and the roaming status of the mobile are further analyzed.

Call Flow:

When A subscriber is calling B subscriber, the call flows in the following way to reach destination.

A subscriber dials B number, the call goes to Pre-Analysis. In pre-analysis, it finds whether it is a service call, emergency call or normal call.

It identifies the A subscriber dialed a normal call and it is sent to Tree Analysis. As it is a MOC, it selects tree2 and it is sent to Main Analysis.

In Main Analysis, two major functions have to be performed i.e., Routing Analysis and Charging Analysis.

In Routing Analysis, it decides in which way the call has to be routed as there are no. of sub-destinations

In Charging Analysis, it will charge the A subscriber as per the CDR in the MSC. Finally it goes to Call Barring Analysis, it will decide whether the call has to be

processed to B subscriber or not. As it is a supplementary service in which B subscriber can make use of it, if B subscriber keeps that particular A number to be not allowed, the call can’t be processed to further.

The call reaches the destination.

ATTACH THE TRACES