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
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
2. Main Analysis
3. 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
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
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
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.
• 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:
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
The analysis is done in the following way:
1. Create Digit Analysis
2. Crate Digit Analysis Components
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
5. Create Digit Analysis
Sub-destination Max. 4096
MSC/VLR m 2046percircuitgroup
Circuit GroupCircuit Group
Hunting GroupHunting Group
• 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
• Each route consists of a maximum of eight circuit groups, which are characterized by
• 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
When A subscriber is calling B subscriber, the call flows in the following way to reach
• 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