This chapter is designed to provide the student with the
knowledge of how a mobile originating call is handled in the
MSC/VLR.
OBJECTIVES: Upon completion of this chapter the student will be able to:
•  Explain how a mobile originated call is analyzed
•  Describe how a mobile originated emergency call is analyzed in the
MSC/VLR
 
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Table of Contents
EMERGENCY CALLS........................................................................ 142
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GENERAL
In this chapter, the exchange data necessary to allow a mobile
originated call is described. Many of the areas of analysis, for
example, B-number analysis, access barring analysis, and routing
case analysis ought to be familiar from previous chapters and
courses, therefore, only new or different aspects will be
considered in further detail.
Figure 9-1  shows the nodes and information involved in a
mobile originated call.
Analysis checks of
BSCMSC
1
2
The following sequence of events occurs:
1.  The MS sends a DTAP message to the MSC which contains
Bearer Capability (BC), the B-number, and other information
describing the B-number. The other information includes the
B-Number Type (BNT) and the Numbering Plan (NP). The
Bearer Capability (BC) describes the type of service required
for the call, for example, it may be a telephony call, a fax
 
 – 138 –  EN/LZT 123 3976 R7A
Plan (NP) always indicates that the B-number is based on the
E.164 series, NP=1 and the B-Number Type (BNT) usually
indicates that the B-number is of type unknown, BNT=2.
However, if the “+” key (the “+” key is used instead of the
international access code, in Germany 00, Sweden 009) is
used BNT indicates that the B-number is in the international
format BNT=1.
2.  The whole range of analysis takes place in the MSC/VLR, as
illustrated in Figure 9-2, before an outgoing route is selected.
3.  The call is routed to other networks according to the B-
number and Routing Case analysis.
 
ANALYSIS FUNCTIONS
For a mobile originated call to be routed, a number of analysis
functions is required, refer to Figure 9-2 .
Access Barring
IMSI Origin
Analysis of B-Number
Figure 9-2 Analysis Functions 
In addition to the analysis functions, shown in Figure 9-2,  the
aforementioned telecommunication service analysis must take
place. The purpose of the telecommunication service analysis is
to determine whether the MSC/VLR supports this call type. If the
MSC/VLR does not have a GIWU or a DTI, any data or fax calls
will fail due to the fact that the GIWU or DTI is required to
support the call. For more information about telecommunication
service analysis, refer to Chapter 7 “Telecommunication Service
Analysis”.
IMSI NUMBER SERIES ANALYSIS 
Analysis of B-Number
Information about the MS is fetched from the IMSI number
series analysis table. This information includes these parameters:
OBA
Origin of B-number Analysis, specifies which B-origin the MS
should use for the mobile originated call in the Pre-analysis, or in
the B-number Analysis.
Call Barring Access, this parameter is used in connection with
the supplementary service, BOIEXH (Barring of all Outgoing
International calls EXcept those directed towards the Home
PLMN).
NATMS 
 
OWNMS 
COLP/COLR supplementary service can be used.
All these parameters are defined using the ANRES parameter, a
copy is found in the Application Information (AI) for Mobile
Telephony Data. To find the parameter values, or to get an
explanation of the parameter, refer to the Application
Information (AI) for the parameter owning block, for example,
the owning block for NATMS, is MTACC (for mobile
originated calls), or MTBSS (for mobile terminated calls).
Figure 9-4  shows an example of the result of an IMSI-number
analysis.
  OPERATING TABLE
BO-30
MAPVER-1
CBA-49
Chapter 5 “Location Updating”.
EMERGENCY CALLS
Personal Communications Service (PCS), the emergency call
number is 112. When this number is dialed, the Connection
Management (CM) Service request message from the MS
indicates that this is an emergency call establishment.
An End of Selection (ES) code is generated:
•  2290 if the call is to be set-up with a SIM-card
•  2577 if no SIM-card is installed in the MS
 This ES code is converted into a B-number which is then
analyzed in the ordinary B-number table. The output of this
analysis is a Routing Case (RC).
 Emergency call routing is determined by the RC, Routing Origin
(RO) parameter, and the Emergency Area (EA) parameter.
 Figure 9-5  shows the printout from a Routing Case (RC)
analysis table for Routing Case (RC) 96.
 
  RO-0
EA-2
 Figure 9-5 
9 Call from Mobile Subscriber 
EN/LZT 123 3976 R7A  – 143 – 
 The cell where the MS is located at call set-up determines RO
 
C6A31 262-02-60-4 BSC6A4 1 0 1
C6A32 262-02-61-5 BSC6A4 2 0 1
C6B31 262-02-62-6 BSC6B4 3 0 2
C6B31 262-02-63-9 BSC6B4 3 0 2
 Figure 9-6 
 Exchange properties determine how an emergency call is set up:
•  EMCNOIMSI — determines whether an emergency call is
allowed without  a SIM-card.
carried out when location updating has not  been made, when
a SIM-card is installed in the MS.
•  IMEICONTROLEMR — determines if the IMEI check 
should be performed for a mobile originated emergency call.
•  IMEIROUTGRYEMR — determines if an emergency call
should be rerouted to announcement or operator, in case the
MS is not type-approved (gray listed).
For more information concerning exchange properties, refer to
Application Information (AI) 1/APT.
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