Basic Call Handling GSM 03.18

Page 1GSM 03.18 Version 2.1.0: February 1997

GSM GSM 03.18

TECHNICAL February 1997

SPECIFICATION Version 2.1.0

Source: ETSI TC-SMG Reference: TS/SMG-0xxxxxQ

ICS: 33.020

Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)

GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS

R

Digital cellular telecommunications system (Phase 2+);Basic call handling

Technical Realisation(GSM 03.18)

ETSI

European Telecommunications Standards Institute

ETSI Secretariat

Postal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [email protected]

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Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 1997. All rights reserved.


Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to"ETSI Editing and Committee Support Dept." at the address shown on the title page.


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Contents

Foreword....................................................................................................................................................... 8

1 Scope....................................................................................................................................................... 10

2 Normative references............................................................................................................................... 10

3 Definitions, symbols and abbreviations.................................................................................................... 113.1 Definitions ................................................................................................................................... 113.2 Abbreviations .............................................................................................................................. 12

4 Architecture.............................................................................................................................................. 134.1 Architecture for an MO call ......................................................................................................... 134.2 Architecture for an MT call.......................................................................................................... 14

5 Information flows...................................................................................................................................... 155.1 Information flow for an MO call ................................................................................................... 155.2 Information flow for retrieval of routeing information for an MT call ........................................... 175.3 Information flow for an MT call ................................................................................................... 18

6 Principles for interactions with supplementary services........................................................................... 206.1 Line identification services (GSM 03.81) .................................................................................... 20

6.1.1 Calling Line Identification Presentation (CLIP)......................................................... 206.1.2 Calling Line Identification Restriction (CLIR)............................................................ 206.1.3 Connected Line Identification Presentation (COLP)................................................. 206.1.4 Connected Line Identification Restriction (COLR) ................................................... 20

6.2 Call forwarding services (GSM 03.82) ........................................................................................ 206.2.1 Call Forwarding Unconditional (CFU)....................................................................... 206.2.2 Call Forwarding on mobile subscriber Busy (CFB) .................................................. 206.2.3 Call Forwarding on No Reply (CFNRy) .................................................................... 206.2.4 Call Forwarding on mobile subscriber Not Reachable (CFNRc).............................. 20

6.3 Call wait (GSM 03.83)................................................................................................................. 216.4 Call hold (GSM 03.83) ................................................................................................................ 216.5 Multiparty (GSM 03.84)............................................................................................................... 216.6 Closed user group (GSM 03.85)................................................................................................. 216.7 Advice of charge (GSM 03.86) ................................................................................................... 216.8 Call barring (GSM 03.88)............................................................................................................ 21

6.8.1 Barring of outgoing calls........................................................................................... 216.8.2 Barring of incoming calls .......................................................................................... 21

6.9 Explicit Call Transfer (GSM 03.91) ............................................................................................. 21

7 Functional requirements of network entities ............................................................................................ 227.1 MO call........................................................................................................................................ 22

7.1.1 Functional requirements of serving MSC ................................................................. 227.1.1.1 Process OCH_MSC.......................................................................... 227.1.1.2 Procedure Process_Access_Request_MSC .................................... 227.1.1.3 Procedure Set_CLI_Presentation_Indicator_MSC ........................... 237.1.1.4 Procedure Set_COLP_Info_MSC..................................................... 237.1.1.5 Procedure Handle_AoC_MO_MSC .................................................. 237.1.1.6 Procedure Obtain_IMSI_MSC .......................................................... 237.1.1.7 Procedure Authenticate_MSC .......................................................... 237.1.1.8 Procedure Obtain_IMEI_MSC .......................................................... 237.1.1.9 Procedure Check_IMEI_MSC........................................................... 23

7.1.2 Functional requirements of VLR............................................................................... 387.1.2.1 Process OCH_VLR........................................................................... 387.1.2.2 Procedure Process_Access_Request_VLR ..................................... 387.1.2.3 Procedure Check_BAOC.................................................................. 387.1.2.4 Procedure OG_CUG_Check ............................................................ 38


7.1.2.5 Procedure Check_OG_Barring .........................................................387.1.2.6 Procedure Get_LI_Subscription_Info_MO_VLR ...............................387.1.2.7 Procedure Get_AoC_Subscription_Info_VLR ...................................387.1.2.8 Procedure Obtain_Identity_VLR........................................................387.1.2.9 Procedure Obtain_IMSI_VLR............................................................387.1.2.10 Procedure Authenticate_VLR..........................................................387.1.2.11 Procedure Obtain_Authentication_Sets_VLR .................................397.1.2.12 Procedure Start_Tracing_VLR ........................................................397.1.2.13 Procedure Check_IMEI _VLR .........................................................397.1.2.14 Procedure Obtain_IMEI _VLR.........................................................397.1.2.15 Process Fetch_Authentication_Sets_VLR ......................................39

7.2 Retrieval of routeing information for MT call ...............................................................................647.2.1 Functional requirements of GMSC ...........................................................................64

7.2.1.1 Process MT_GMSC ..........................................................................647.2.1.2 Procedure Handle_COLP_Forwarding_Interaction_MSC.................64

7.2.2 Functional requirements of HLR ...............................................................................697.2.2.1 Process SRI_HLR .............................................................................697.2.2.2 Procedure Check_Parameters..........................................................697.2.2.3 Procedure Subscription_Check_HLR................................................697.2.2.4 Procedure First_Forwarding_HLR.....................................................697.2.2.5 Procedure PRN_Error_HLR..............................................................697.2.2.6 Procedure Forward_CUG_Check .....................................................697.2.2.7 Procedure Derive_Requested_Basic_Service_HLR.........................697.2.2.8 Procedure Check_IC_Barring ...........................................................697.2.2.9 Procedure IC_CUG_Check ...............................................................697.2.2.10 Procedure Handle_CFU ..................................................................697.2.2.11 Procedure Handle_CFNRc..............................................................69

7.2.3 Functional requirements of VLR ...............................................................................837.2.3.1 Process PRN_VLR............................................................................837.2.3.2 Process Restore_Subscriber_Data_VLR..........................................837.2.3.3 Process PSI_VLR..............................................................................83

7.2.4 Functional requirements of MSC ..............................................................................907.2.4.1 Process OSI_MSC ............................................................................90

7.3 MT call.........................................................................................................................................927.3.1 Functional requirements of serving MSC..................................................................92

7.3.1.1 Process ICH_MSC ............................................................................927.3.1.2 Procedure Page_MS_MSC ...............................................................927.3.1.3 Procedure Search_For_MS_MSC.....................................................937.3.1.4 Procedure Complete_Call_In_MSC ..................................................937.3.1.5 Procedure Process_Call_Waiting_MSC ...........................................937.3.1.6 Procedure Set_CLIP_Info_MSC .......................................................937.3.1.7 Procedure Derive_GSM_BC_MSC ...................................................937.3.1.8 Procedure Handle_AoC_MT_MSC ...................................................937.3.1.9 Procedure Set_COL_Presentation_Indicator_MSC..........................93

7.3.2 Functional requirements of VLR .............................................................................1147.3.2.1 Process ICH_VLR ...........................................................................1147.3.2.2 Procedure Derive_Requested_Basic_Service_VLR .......................1147.3.2.3 Procedure Search_For_MS_VLR....................................................1147.3.2.4 Procedure Get_CW_Subscription_Info_VLR..................................1147.3.2.5 Procedure Get_LI_Subscription_Info_MT_VLR..............................1147.3.2.6 Procedure Handle_CFB ..................................................................1147.3.2.7 Procedure Handle_CFNRy..............................................................114

8 Contents of messages............................................................................................................................1278.1 Messages on the B interface (MSC-VLR) .................................................................................127

8.1.1 Abort 1278.1.2 Authenticate ............................................................................................................1278.1.3 Authenticate ack .....................................................................................................1278.1.4 Check IMEI .............................................................................................................1278.1.5 Check IMEI ack.......................................................................................................1278.1.6 Check IMEI negative response...............................................................................1278.1.7 Complete Call .........................................................................................................1288.1.8 Complete Call ack...................................................................................................130


8.1.9 Complete Call negative response .......................................................................... 1308.1.10 Forward New TMSI .............................................................................................. 1308.1.11 Forward New TMSI ack........................................................................................ 1308.1.12 Forward New TMSI negative response................................................................ 1308.1.13 Obtain Subscriber Info.......................................................................................... 1308.1.14 Obtain Subscriber Info ack................................................................................... 1308.1.15 Page MS............................................................................................................... 1308.1.16 Page MS negative response ................................................................................ 1318.1.17 Process Access Request ..................................................................................... 1318.1.18 Process Access Request ack............................................................................... 1318.1.19 Process Access Request negative response....................................................... 1328.1.20 Process Call Waiting ............................................................................................ 1328.1.21 Process Call Waiting ack ..................................................................................... 1328.1.22 Process Call Waiting negative response.............................................................. 1328.1.23 Provide IMEI......................................................................................................... 1328.1.24 Provide IMEI ack .................................................................................................. 1328.1.25 Provide IMSI......................................................................................................... 1338.1.26 Provide IMSI ack .................................................................................................. 1338.1.27 Search For MS ..................................................................................................... 1338.1.28 Search For MS ack .............................................................................................. 1338.1.29 Search For MS negative response....................................................................... 1338.1.30 Send Info For Incoming Call................................................................................. 1338.1.31 Send Info For Incoming Call ack .......................................................................... 1348.1.32 Send Info For Incoming Call negative response .................................................. 1348.1.33 Send Info For Outgoing Call................................................................................. 1358.1.34 Send Info For Outgoing Call negative response .................................................. 1358.1.35 Set ciphering mode .............................................................................................. 1358.1.36 Trace subscriber activity....................................................................................... 1358.1.37 Use existing TMSI ................................................................................................ 135

8.2 Messages on the C interface (MSC-HLR) ................................................................................ 1368.2.1 Send Routeing Info................................................................................................. 1368.2.2 Send Routeing Info ack .......................................................................................... 1368.2.3 Send Routeing Info negative response .................................................................. 136

8.3 Messages on the D interface (VLR-HLR) ................................................................................. 1378.3.1 Provide Roaming Number...................................................................................... 1378.3.2 Provide Roaming Number ack ............................................................................... 1378.3.3 Provide Roaming Number negative response ....................................................... 1378.3.4 Provide Subscriber Info .......................................................................................... 1388.3.5 Provide Subscriber Info ack ................................................................................... 138

8.3.5.1 Location information ....................................................................... 1388.3.8 Provide Subscriber Info negative response............................................................ 1398.3.6 Restore Data .......................................................................................................... 1398.3.7 Restore Data ack ................................................................................................... 1398.3.8 Restore Data negative response............................................................................ 1398.3.9 Provide Subscriber Info negative response............................................................ 139

8.4 Messages on the F interface (MSC-EIR).................................................................................. 1398.4.1 Check IMEI............................................................................................................. 1398.4.2 Check IMEI ack ...................................................................................................... 1398.4.3 Check IMEI negative response .............................................................................. 139

Annex A (Informative) Handling of an IAM at an MSC.............................................................................. 141

History....................................................................................................................................................... 144


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Foreword

This ETSI GSM Technical Specification has been produced by the TC SMG Technical Committee of theEuropean Telecommunications Standards Institute (ETSI).


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1 Scope

This standard specifies the technical realisation of the handling of calls originated by a GSM mobilesubscriber and calls directed to a GSM mobile subscriber, up to the point where the call is established.Normal release of the call after establishment is also specified.

The handling of DTMF signalling and Off-Air Call setup (OACSU) are not described in this specification.

The details of the effects of GSM supplementary services on the handling of a call are described in therelevant GSM 03.8x and GSM 03.9x series of specifications.

The specification of the handling of a request from the HLR for subscriber information is not part of basiccall handling, but is required for both CAMEL [5] and optimal routeing [6]. The use of the ProvideSubscriber Information message flow is shown in [5] and [6].

The logical separation of the MSC and VLR (shown in clauses 4, 5 & 7), and the messages transferredbetween them (described in clause 8) are the basis of a model used to define the externally visiblebehaviour of the MSC/VLR, which is a single physical entity. They do not impose any requirement exceptthe definition of the externally visible behaviour.

If there is any conflict between this specification and the corresponding stage 3 specifications ([14], [16] &[17]), the stage 3 specification shall prevail.

2 Normative references

[1] ETS 300 500 (1994): " European digital cellular telecommunications system(Phase 2); Principles of telecommunication services supported by a GSM PublicLand Mobile Network (PLMN) (GSM 02.01)”.

[2] ETS 300 523 (1994): " European digital cellular telecommunications system(Phase 2); Numbering, addressing & identification (GSM 03.03)”.

[3] ETS 300 534 (1994): " European digital cellular telecommunications system(Phase 2); Security related network functions (GSM 03.20)”.

[4] GSM 03.32: " Digital cellular telecommunications system (Phase 2+); UniversalGeographical Area Description (GAD) (GSM 03.32)”.

[5] GSM 03.78: “Digital cellular telecommunications system (phase 2+);Customised Applications for Mobile network Enhanced Logic (CAMEL) (GSM03.78)”

[6] GSM 03.79: “European digital cellular telecommunications system (Phase 2+);Support of Optimal Routeing (SOR) Technical Realisation (GSM 03.79)

[7] ETS 300 542 (1994): " European digital cellular telecommunications system(Phase 2); Line identification supplementary services - Stage 2 (GSM 03.81)”.

[8] ETS 300 543 (1994): “European digital cellular telecommunications system(Phase 2); Call Forwarding (CF) supplementary services - Stage 2 (GSM03.82)”.

[9] ETS 300 544 (1994): “European digital cellular telecommunications system(phase 2); Call Waiting (CW) and Call Hold (HOLD) supplementary services -Stage 2 (GSM 03.83)”.

[10] ETS 300 545 (1994): “European digital cellular telecommunications system(phase 2); Multi Party (MPTY) supplementary services - Stage 2 (GSM 03.84)”.

[11] ETS 300 546 (1994): “European digital cellular telecommunications system(phase 2); Closed User Group (CUG) supplementary services - Stage 2 (GSM03.85)”.


[12] ETS 300 547 (1994): “European digital cellular telecommunications system(phase 2); Advice of Charge (AoC) supplementary services - Stage 2 (GSM03.86)”.

[13] ETS 300 548 (1994): “European digital cellular telecommunications system(Phase 2); Call Barring (CB) supplementary services - Stage 2 (GSM 03.88)”

[14] ETS 300 557 (1995): “European digital cellular telecommunications system(Phase 2); Mobile radio interface layer 3 specification (GSM 04.08)”

[15] ETS 300 582 (1994): “European digital cellular telecommunications system(Phase 2); General on Terminal Adaptation Functions (TAF) for Mobile Stations(MS) (GSM 07.01)”

[16] ETS 300 590 (1995): “European digital cellular telecommunications system(Phase 2); Mobile-services Switching Centre - Base Station System (MSC -BSS) interface Layer 3 specification (GSM 08.08)”

[17] ETS 300 599 Fourth Edition (1996): “European digital cellulartelecommunications system (Phase 2); Mobile Application Part (MAP)specification (GSM 09.02)”

[18] ETS 300 604 (1994): “European digital cellular telecommunications system(Phase 2); General requirements on interworking between the Public LandMobile Network (PLMN) and the Integrated Services Digital Network (ISDN) orPublic Switched Telephone Network (PSTN) (GSM 09.07)”

[19] ETS 300 607 (1994): “European digital cellular telecommunications system(Phase 2); Information element mapping between Mobile Station - Base StationSystem (MS - BSS) and Base Station System - Mobile-services SwitchingCentre (BSS - MSC) Signalling procedures and the Mobile Application Part(MAP) (GSM 09.10)”

[20] ETS 300 627 (1996): “European digital cellular telecommunications system(Phase 2); Subscriber and equipment trace (GSM 12.08)”

[21] ETS 300 356-1 (1995): “Integrated Services Digital Network (ISDN); SignallingSystem No. 7; ISDN User Part (ISUP) version 2 for the international interface;Part 1: Basic services”

[22] ITU-T Recommendation Q.850 (1996): “Usage of cause and location in theDigital Subscriber Signalling System No. 1 and the Signalling System No. 7ISDN User Part”

3 Definitions, symbols and abbreviations

3.1 Definitions

A subscriber: The calling mobile subscriber.

B subscriber: The mobile subscriber originally called by the A subscriber.

C subscriber: The subscriber to whom the B subscriber has requested that calls be forwarded. The Csubscriber may be fixed or mobile.

Location Information: Information to define the whereabouts of the MS, and the age of the informationdefining the whereabouts.


3.2 Abbreviations

A&O Active & OperativeACM Address Complete MessageANM ANswer MessageAoC Advice of ChargeBC Bearer CapabilityBOIC-exHC&BOIZC Barring of Outgoing International Calls except those directed to the HPLMN

Country & Barring of Outgoing InterZonal CallsBOIZC Barring of Outgoing InterZonal CallsBOIZC-exHC Barring of Outgoing InterZonal Calls except those directed to the HPLMN

CountryCFB Call Forwarding on BusyCFNRc Call Forwarding on mobile subscriber Not ReachableCFNRy Call Forwarding on No ReplyCFU Call Forwarding UnconditionalCLIP Calling Line Identity PresentationCLIR Calling Line Identity RestrictionCOLP COnnected Line identity PresentationCOLR COnnected Line identity RestrictionCUG Closed User GroupCW Call WaitingFTN Forwarded-To NumberFTNW Forwarded-To NetWorkGMSCB Gateway MSC of the B subscriberHLC Higher Layer CompatibilityHLRB The HLR of the B subscriberHPLMNB The HPLMN of the B subscriberIAM Initial Address MessageIPLMN Interrogating PLMN - the PLMN containing GMSCBLLC Lower Layer CompatibilityMO Mobile OriginatedMPTY MultiParTYMT Mobile TerminatedNDUB Network Determined User BusyNRCT No Reply Call TimerPRN Provide Roaming NumberSIFIC Send Information For Incoming CallSIFOC Send Information For Outgoing CallSRI Send Routeing InformationUDUB User Determined User BusyVLRA The VLR of the A subscriberVLRB The VLR of the B subscriberVMSCA The Visited MSC of the A subscriberVMSCB The Visited MSC of the B subscriberVPLMNA The Visited PLMN of the A subscriberVPLMNB The Visited PLMN of the B subscriber


4 Architecture

Subclauses 4.1 and 4.2 show the architecture for handling a basic MO call and a basic MT call. A basicmobile-to-mobile call is treated as the concatenation of an MO call and an MT call.

4.1 Architecture for an MO call

A basic mobile originated call involves signalling between the MS and its VMSC via the BSS, between theVMSC and the VLR and between the VMSC and the destination exchange, as indicated in figure 1.

MS

VMSCA

VLRAVPLMNA

Air I/F signalling

SIFOC/ack

IAM (ISUP)BSSA

'A' I/F signalling

Figure 1: Architecture for a basic mobile originated call

In figure 1 and throughout this specification, the term ISUP is used to denote the telephony signallingsystem used between exchanges. In a given network, any telephony signalling system may be used.

When the user of an MS wishes to originate a call, the MS establishes communication with the networkusing air interface signalling, and sends a message containing the address of the called party. VMSCArequests information to handle the outgoing call (SIFOC) from VLRA, over an internal interface of theMSC/VLR. If VLRA determines that the outgoing call is allowed, it responds with a SIFOC ack. VMSCA:

- establishes a traffic channel to the MS, and- constructs an ISUP IAM using the called party address and sends it to the destination exchange.


4.2 Architecture for an MT call

A basic mobile terminated call involves signalling as indicated in figure 2. Communication betweenVMSCB and the MS is via the BSS, as for the mobile originated case. The IPLMN, containing GMSCB, isin principle distinct from HPLMNB, containing HLRB, but the practice for at least the majority of currentGSM networks is that a call to a GSM MS will be routed to a GMSC in HPLMNB.

IPLMN

GMSCB

VPLMNB

HLRB

HPLMNB

IAM(ISUP)

IAM(ISUP)

Send RouteingInfo/ack

Provide RoamingNumber/ack

Air I/Fsignalling

MS

VLRB

VMSCB

SIFICPage/ackComplete call

BSSB

'A' I/Fsignalling

Figure 2: Architecture for a basic mobile terminated call

When GMSCB receives an ISUP IAM, it requests routeing information from HLRB using the MAPprotocol. HLRB requests a roaming number from VLRB, also using the MAP protocol, and VLRB returns aroaming number in the Provide Roaming Number Ack. HLRB returns the roaming number to GMSCB inthe Send Routeing Info ack. GMSCB uses the roaming number to construct an ISUP IAM, which it sendsto VMSCB. When VMSCB receives the IAM, it requests information to handle the incoming call (SIFIC)from VLRB, over an internal interface of the MSC/VLR. If VLRB determines that the incoming call isallowed, it requests VMSCB to page the MS. VMSCB pages the MS using air interface signalling. Whenthe MS responds, VMSCB informs VLRB in the Page ack message. VLRB instructs VMSCB to connectthe call in the Complete call, and VMSCB establishes a traffic channel to the MS.


5 Information flows

5.1 Information flow for an MO call

An example information flow for an MO call is shown in figure 3; many variations are possible. Signallingover the air interface between MSA and BSSA or VMSCA is shown by dotted lines; signalling over the ‘A’interface between BSSA and VMSCA is shown by dashed lines; signalling over the B interface betweenVMSCA and VLRA is shown by chain lines; and ISUP signalling between VMSCA and the destinationexchange is shown by solid lines.

MSA BSSA VMSCA VLRA

CM service req

Authenticate

Authenticate resp

Cipher mode cmd(note 3)

Cipher mode comp

Setup

Call proceeding

Assignment cmd

Assignment comp

Connect ack

CM service req

Authenticate

Authenticate ack

Start ciphering(note 3)

Cipher mode comp

Allocate channel

Allocation complete

Alert

Connect

Process access req

Authenticate(note 1)

Authenticate ack

Set cipher mode(note 2)

Process access req

SIFOC

Complete call

IAM

ACM

ANM

Authenticateaccept

ack

Figure 3: Information flow for a basic mobile originated call


NOTE 1: Authentication may occur at any stage during the establishment of an MO call; itsposition in this message flow diagram is an example.

NOTE 2: Ciphering may be initiated at any stage after authentication; its position in thismessage flow diagram is an example.

NOTE 3: If ciphering is not required, the MSC may send a CM service accept towards the MS;optionally it may instead send a ‘start ciphering’ request indicating that no ciphering isrequired.

NOTE 4: The network may request the IMEI from the MS, and may check the IMEI, at any stageduring the establishment of an MO call, either as part of the procedure to startciphering or explicitly after ciphering has started; this is not shown in this message flowdiagram.

When the user wishes to originate a call, MSA establishes a signalling connection with BSSA, and sendsa Connection Management (CM) service request to BSSA, which relays it to VMSCA. VMSCA sends aProcess access request to VLRA. VLRA may then initiate authentication, as described in [3]. VLRA mayalso initiate ciphering at this stage, as described in [3].

If VLRA determines that MSA is allowed service, it sends a Process access request ack to VMSCA. IfVMSCA has received a Set cipher mode message from VLRA, the Process access request ack messagetriggers a Start ciphering command message towards BSSA; otherwise VMSCA sends a CM serviceaccept message towards BSSA.

If BSSA receives a Start ciphering command from VMSCA, it initiates ciphering as described in [3]; whenciphering is successfully initiated, MSA interprets this in the same way as a CM service accept. Ifciphering is not required at this stage, BSSA relays the CM service accept to MSA.

When MSA has received the CM service accept, or ciphering has been successfully initiated, MSA sendsa Setup message containing the B subscriber address via BSSA to VMSCA. MSA also uses the Setupmessage to indicate the bearer capability required for the call; VMSCA translates this bearer capability intoa GSM basic service, and determines whether an interworking function is required. VMSCA sends toVLRA a request for information to handle the outgoing call, using a Send Info For Outgoing Call (SIFOC)message containing the B subscriber address.

If VLRA determines that the call should be connected, it sends a Complete Call message to VMSCA.VMSCA sends a Call Proceeding message via BSSA to MSA, to indicate that the call request has beenaccepted, and sends an Allocate channel message to BSSA, to trigger BSSA and MSA to set up a trafficchannel over the air interface. The Call Proceeding message includes bearer capability information if anyof the negotiable parameters of the bearer capability has to be changed. When the traffic channelassignment process is complete (indicated by the Allocation complete message from BSSA to VMSCA),VMSCA constructs an ISUP IAM using the B subscriber address, and sends it to the destinationexchange.

When the destination exchange returns an ISUP Address Complete Message (ACM), VMSCA sends anAlert message via BSSA to MSA, to indicate to the calling user that the B subscriber is being alerted.

When the destination exchange returns an ISUP ANswer Message (ANM), VMSCA sends a Connectmessage via BSSA to MSA, to instruct MSA to connect the speech path.

The network then waits for the call to be cleared.

For an emergency call, a different CM service type (emergency call) is used, and the mobile may identifyitself by an IMEI. It is a network operator option whether to allow an emergency call when the mobileidentifies itself by an IMEI. Details of the handling are shown in clause 7.


5.2 Information flow for retrieval of routeing information for an MT call

The information flow for retrieval of routeing information for an MT call is shown in figure 4. ISUPsignalling between the originating exchange and GMSCB, and between GMSCB and VMSCB is shown bysolid lines; signalling over the MAP interfaces between GMSCB and HLRB and between HLRB and VLRBis shown by chain lines.

GMSCB HLRB VLRB VMSCBIAM

SRIPRN

SRI ackPRN ack

IAM

Figure 4: Information flow for retrieval of routeing information for a basic mobile terminated call

When GMSCB receives an IAM, it analyses the called party address. If GMSCB can derive an HLRaddress from the B party address, it sends a request for routeing information (SRI) to HLRB. HLRB sendsa request for a roaming number (PRN) to VLRB. VLRB returns the roaming number in the PRN ack, andHLRB relays the roaming number to GMSCB in the SRI ack. GMSCB constructs an IAM using theroaming number, and sends it to VMSCB.


5.3 Information flow for an MT call

An example information flow for an MT call is shown in figure 5; many variations are possible. ISUPsignalling between GMSCB and VMSCB is shown by solid lines; signalling over the B interface betweenVMSCB and VLRB is shown by chain lines; signalling over the ‘A’ interface between VMSCB and BSSB isshown by dashed lines; and signalling over the air interface between VMSCB or BSSB and MSB is shownby dotted lines.

GMSCB VLRB VMSCB BSSB MSBIAM

SIFIC

Page MSPage

Page

Chan req

Imm ass

Page respMS conn

estabProcessaccess req

Set ciphermode (note 1)

Process

access req ack Startciphering(note 2)

Complete call

Cipher mode

commandCipher mode

completeSetup

Call conf

Allocatechannel

Assignment

command

complete

AssignmentAllocationcomplete

AlertingACM

ANMConnect

Complete callConnect ack

ack

Figure 5: Information flow for a basic mobile terminated call

NOTE 1: Ciphering may be initiated at any stage after the network has accepted the pageresponse; its position in this message flow diagram is an example.


NOTE 2: If ciphering is not required, the MSC may send a ‘start ciphering’ request indicating thatno ciphering is required.

NOTE 3: This message flow diagram assumes that the MS has already been authenticated onlocation registration. If this is not so (for the first MT call after VLR restoration), thenetwork may initiate authentication after the MS responds to paging.

NOTE 4: The network may request the IMEI from the MS, and may check the IMEI, at any stageafter the MS responds to paging, either as part of the procedure to start ciphering orexplicitly after ciphering has started; this is not shown in this message flow diagram.

When VMSCB receives an IAM from GMSCB it sends to VLRB a request for information to handle theincoming call, using a Send Info For Incoming Call (SIFIC) message containing the roaming numberreceived in the IAM.

If VLRB recognises the roaming number, and MSB is allowed service, it sends a request to VMSCB topage MSB. If a radio connection between the network and MSB is already established, VMSCB respondsimmediately to the page request. If no radio connection exists, VMSCB sends a page request to BSSB,and BSSB broadcasts the page on the paging channel.

If MSB detects the page, it sends a channel request to BSSB, which responds with an immediateassignment command, to instruct MSB to use the specified signalling channel. MSB then sends a pageresponse on the signalling channel; BSSB relays this to VMSCB. VMSCB sends a Process accessrequest message to VLRB to indicate that MSB has responded to paging. VLRB may then initiateauthentication, as described in [3]. VLRB may also initiate ciphering at this stage, as described in [3].

If VLRB determines that MSB is allowed service, it sends a Process access request ack to VMSCB. TheProcess access request ack message triggers a Start ciphering command message towards BSSB; ifVMSCB has not received a Set cipher mode message from VLRB, the Start ciphering command indicatesno ciphering.

VLRB then sends a Complete call message to VMSCB. VMSCB sends a Setup message towards MSB.The Setup message may include bearer capability information for the call.

When MSB receives the Setup message from BSSB, it responds with a Call confirmed message. The CallConfirmed message includes bearer capability information if any of the negotiable parameters of thebearer capability has to be changed. When VMSCB receives the Call confirmed message via BSSB, itsends an Allocate channel message to BSSB. BSSB instructs MSB to tune to a traffic channel by sendingan Assignment command. When MSB has tuned to the specified traffic channel it responds with anAssignment complete, message, which BSSB relays to VMSCB as an Allocation complete, and sends anAlerting message to indicate that the called user is being alerted. VMSCB sends an ACM to GMSCB,which relays it to the originating exchange.

When the called user answers, MSB sends a Connect message, which BSSB relays to VMSCB. VMSCB:

- responds with a Connect ack message towards MSB;- sends an ANM to GMSCB, which relays it to the originating exchange;- sends a Complete call ack to VLRB.

The network then waits for the call to be cleared.


6 Principles for interactions with supplementary services

This clause specifies the principles used to describe the invocation of the GSM supplementary serviceswhich were standardised when this specification was drafted. Registration, erasure, activation,deactivation and interrogation are call-independent operations; they are therefore outside the scope of thisspecification. Descriptions may be found in the stage 2 specifications for each supplementary service.

In the modelling used in this specification, each supplementary service which a network entity supports ismanaged by a supplementary service handler, which handles data in the entity in which it runs. The callhandling processes defined in this specification use the data to define the contents of messages to otherentities. The basic call handling processes defined in this specification interact with the supplementaryservice handlers as shown in the SDL diagrams and the supporting text. If a network entity does notsupport a supplementary service, it bypasses the interaction with the handler for that supplementaryservice. Exceptions to this general principle are described later in this clause.

6.1 Line identification services (GSM 03.81)

6.1.1 Calling Line Identification Presentation (CLIP)

The basic call handling processes ICH_VLR and ICH_MSC interact with the processes CLIP_MAF001and CLIP_MAF002 [7] as described in subclauses 7.3.2 and 7.3.1.

6.1.2 Calling Line Identification Restriction (CLIR)

The basic call handling processes OCH_MSC and OCH_VLR interact with the processes CLIR_MAF004and CLIR_MAF003 [7] as described in subclauses 7.1.1 and 7.1.2.

6.1.3 Connected Line Identification Presentation (COLP)

The basic call handling processes OCH_MSC and OCH_VLR interact with the processes COLP_MAF006and COLP_MAF005 [7] as described in subclauses 7.1.1 and 7.1.2.

The basic call handling processes MT_GMSC and ICH_MSC interact with the process COLP_MAF039 [7]as described in subclauses 7.2.1 and 7.3.1.

6.1.4 Connected Line Identification Restriction (COLR)

The basic call handling processes ICH_VLR and ICH_MSC interact with the processes COLR_MAF040and COLR_MAF041 [7] as described in subclauses 7.3.2 and 7.3.1.

6.2 Call forwarding services (GSM 03.82)

6.2.1 Call Forwarding Unconditional (CFU)

The basic call handling process SRI_HLR interacts with the process MAF007 [8] as described insubclause 7.2.2

6.2.2 Call Forwarding on mobile subscriber Busy (CFB)

The basic call handling process ICH_VLR interacts with the process MAF008 [8] as described insubclause 7.3.2

6.2.3 Call Forwarding on No Reply (CFNRy)

The basic call handling process ICH_VLR interacts with the process MAF009 [8] as described insubclause 7.3.2

6.2.4 Call Forwarding on mobile subscriber Not Reachable (CFNRc)

The basic call handling processes SRI_HLR and ICH_VLR interact with the process MAF010 [8] asdescribed in subclauses 7.2.2 and 7.3.2


6.3 Call wait (GSM 03.83)

The basic call handling process ICH_VLR interacts with the process MAF013 [9] as described insubclause 7.3.2. Further details of the handling of call waiting are given in subclauses 7.3.1 & 7.3.2.

6.4 Call hold (GSM 03.83)

Invocation of call hold before a basic call has been established will be rejected.

6.5 Multiparty (GSM 03.84)

Invocation of multiparty before a basic call has been established will be rejected.

6.6 Closed user group (GSM 03.85)

The basic call handling process OCH_VLR interacts with the process CUG_MAF014 [11] as described insubclause 7.1.2.

The basic call handling process SRI_HLR interacts with the process CUG_MAF015 [11] as described insubclause 7.2.2.

The interactions between call forwarding and CUG [11] are handled as described in subclause 7.2.2.6.

6.7 Advice of charge (GSM 03.86)

The interactions between Advice of Charge [12] and MO calls are handled as described in subclauses7.1.1 and 7.1.2.

The interactions between Advice of Charge [12] and MT calls are handled as described in subclauses7.3.1 and 7.3.2.

6.8 Call barring (GSM 03.88)

6.8.1 Barring of outgoing calls

The basic call handling process OCH_VLR interacts with the processes MAF017, MAF018 and MAF020[13] as described in subclause 7.1.2.

6.8.2 Barring of incoming calls

The basic call handling process SRI_HLR interacts with the processes MAF022 and MAF023 [13] asdescribed in subclause 7.2.2.

6.9 Explicit Call Transfer (GSM 03.91)

There is no interaction between Explicit Call Transfer and the basic call handling described in thisspecification.


7 Functional requirements of network entities

The text in this clause is a supplement to the definition in the SDL diagrams; it does not duplicate theinformation in the SDL diagrams.

The entities described in this clause interwork with other entities over three different types of interface:

- The A interface, used to interwork between the MSC and the BSS or the MS;- The C, D & F interfaces, used to interwork between the MSC & HLR (C), VLR & HLR (D) and MSC

& EIR (F);- Telephony signalling interfaces, used to interwork between an MSC and another exchange.

The protocols used over the A interface are BSSMAP, which is specified in [16], for interworking with theBSS and DTAP, which is specified in [14], for interworking with the MS.

The protocol used over the C, D & F interfaces is MAP, which is specified in [17].

For the purposes of this specification, the protocol used over telephony signalling interfaces is ISUP,which is specified in [21]; other telephony signalling systems may be used instead.

This specification shows the call handling application processes interworking with a protocol handler foreach of the protocols listed above. Each protocol defines supervision timers. If a supervision timer expiresbefore a distant entity responds to a signal, the handling is as defined in the appropriate protocolspecification. In general, the protocol handler reports timer expiry to the application as an error conditionor negative response. Where a timer is shown in this specification, therefore, it is an application timerrather than a protocol timer. Interworking with the protocol handlers uses functional signal names whichdo not necessarily have a one-to-one correspondence with the names of messages used in the protocols.

An MSC which receives an IAM from an originating exchange may react in three different ways:

- It acts as a transit exchange, i.e. it relays the IAM to a destination exchange determined by analysisof the called party address, and thereafter relays other telephony signalling between the originatingand destination exchange until the connection is released. This behaviour is not specific to GSM;

- It acts as a terminating exchange, i.e. it attempts to connect the call to an MS currently registered inthe service area of the MSC;

- It acts as a GMSC, i.e. it interrogates an HLR for information to route the call. If the HLR returnsrouteing information, the MSC uses the routeing information from the HLR to construct an IAM,which it sends to a destination exchange determined by analysis of the routeing information fromthe HLR.

Annex A describes the method which the MSC uses to decide how to process the IAM.

7.1 MO call

7.1.1 Functional requirements of serving MSC

7.1.1.1 Process OCH_MSC

Sheet 1: the MSC converts the GSM bearer capability negotiated between the MSC and the MS to a GSMbasic service according to the rules defined in [15].

Sheet 2, sheet 4: at any stage after the Setup has been received, the MS may terminate the transactionwith the network by sending a Release transaction request.

7.1.1.2 Procedure Process_Access_Request_MSC

Sheet 1, sheet 2: instead of using the explicit procedure Obtain_IMEI_MSC, the MSC may encapsulatethe request for the IMEI in the Start ciphering request; the BSS relays the response in the Cipher Modecomplete message to the MSC.

Sheet 2: the MSC maps the negative response received on the B interface to the appropriate reject causeaccording to the rules defined in [19].


Sheet 2: The Start ciphering request may indicate one of several ciphering algorithms, or no ciphering.

Sheet 2, sheet 3: At any stage, the MS may terminate the transaction with the network by sending a CMservice abort message.

Sheet 2, sheet 3: if the MSC receives a Setup message from the MS while the access request is beinghandled, the message is saved for processing after the access request has been handled.

7.1.1.3 Procedure Set_CLI_Presentation_Indicator_MSC

The MS may terminate the transaction with the network by sending a Release transactionmessage while aresponse is awaited from the process CLIR_MAF004. The message is saved for processing after returnfrom the procedure.

7.1.1.4 Procedure Set_COLP_Info_MSC

The MS may terminate the transaction with the network by sending a Release transactionmessage while aresponse is awaited from the process COLP_MAF006. The message is saved for processing after returnfrom the procedure.

7.1.1.5 Procedure Handle_AoC_MO_MSC

The charging parameters and the Boolean variable Acknowledgment required are global data which canbe read by the parent process.

7.1.1.6 Procedure Obtain_IMSI_MSC

The MS may terminate the transaction with the network while the MSC is waiting for the MS to return itsIMSI. If a CC connection has not been established, the MS uses CM Service Abort; otherwise it uses aRelease, Release Complete or Disconnect. The MSC aborts the transaction with the VLR and returns anaborted result to the parent process.

7.1.1.7 Procedure Authenticate_MSC

The MS may terminate the transaction with the network while the MSC is waiting for the MS to respond toan authentication request. If a CC connection has not been established, the MS uses CM Service Abort;otherwise it uses a Release, Release Complete or Disconnect. The MSC aborts the transaction with theVLR and returns an aborted result to the parent process.

7.1.1.8 Procedure Obtain_IMEI_MSC

The MS may terminate the transaction with the network while the MSC is waiting for the MS to return itsIMEI. If a CC connection has not been established, the MS uses CM Service Abort; otherwise it uses aRelease, Release Complete or Disconnect. The MSC aborts the transaction with the VLR and returns anaborted result to the parent process.

7.1.1.9 Procedure Check_IMEI_MSC

The MS may terminate the transaction with the network while the MSC is waiting for the MS to return itsIMEI. If a CC connection has not been established, the MS uses CM Service Abort; otherwise it uses aRelease, Release Complete or Disconnect. The MSC aborts the transaction with the VLR and returns anaborted result to the parent process.

The MS may terminate the transaction with the network while the MSC is waiting for the result of the IMEIcheck from the EIR. If a CC connection has not been established, the MS uses CM Service Abort;otherwise it uses a Release, Release Complete or Disconnect. The MSC aborts the transaction with theVLR and returns an aborted result to the parent process.


Process in the MSC tohandle an outgoing call request

Process OCH_MSC OCH_MSC1(4)

Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR.

Idle

CMservicerequest

Process_Access_

Request_MSC

Result=Pass?

Wait_For_Setup

Setup

Convert GSM BC to

basic service

Send Info ForOutgoing Call

Wait_For_MO_Call_

Result

CMServiceAbort

Releasecall

resources

Idle

Yes

No

Figure 6a: Process OCH_MSC (sheet 1)




Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLRunless marked otherwise

Wait_For_MO_Call_

Result

Releasetransaction

Abort

ReleaseCall

Resources

Idle

CompleteCall

Convert GSM BC to channel

requirement

CallProceeding

Allocatechannel

Wait_For_Allocation_Complete

Release transaction

ReleaseCall

Resources

Idle

Allocation failure

Release transaction

Allocationcomplete

Set_CLI_Presentation_

Indicator_MSC

Result=call allowed?

InitialAddress

Towardsdestinationexchange

Wait_For_ACM

Send Info ForOutgoing Callnegative response

Releasetransaction

ReleaseCall

Resources

Idle

No

Yes

Figure 6b: Process OCH_MSC (sheet 2)




Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the destination exchange.

Wait_For_ACM

AddressComplete

Alert

Wait_For_ANM

Answer

Set_COLP_Info_MSC

Handle_AoC_MO_MSC

Connect

Acknowledgmentrequired?

Wait_For_Connect_Ack

ConnectAck

Wait_For_Clear

Start AoCacknowledgment

timer

Wait_For_AoC_Ack

Connect

Wait_For_AoC_Ack

ChargingParametersack

Releasetransaction

Release

Releasecall

resources

Idle

ConnectAck

Releasetransaction

AoCacknowledgmenttimer expired

No

Yes

Figure 6c: Process OCH_MSC (sheet 3)




Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the destination exchange

Wait_For_ACM,Wait_For_ANM,Wait_For_Connect_Ack,Wait_For_Clear

Releasetransaction

ReleaseTowardsdestinationexchange

Releasecall

resources

Idle

ReleaseFrom destinationexchange

Releasetransaction

Figure 6d: Process OCH_MSC (sheet 4)


Procedure in the MSCto handle a request from the MS for system access

Procedure Process_Access_Request_MSC PAR_MSC1(3)


ProcessAccessRequest

Wait_For_PAR_Result

ProvideIMSI

Obtain_IMSI_MSC

Result=Pass?

Result:=Fail

Wait_For_PAR_Result

Authenticate

Authenticate_MSC

Result=Pass?

Result:=Fail

Wait_For_PAR_Result

TraceSubscriberActivity

Tracing Active:=TRUE

Wait_For_PAR_Result

Wait_For_PAR_Result

CMserviceabort

Abort

Result:=Fail

SetCipheringMode

CipheringRequired:=

TRUE

Wait_For_PAR_Result

No

Yes

No

Yes

Figure 7a: Procedure Process_Access_Request_MSC (sheet 1)





Wait_For_PAR_Result

Abort

CM Service type=Page Response?

Map negative response toreject cause

CM ServiceReject

Result:=Fail

Releasetransaction

Process AccessRequest negative response

ProcessAccessRequest ack

Cipheringrequired?

CM Service type=Page Response?

Wait_For_TMSI_

Reallocation

CMserviceabort

Abort

Result:=Fail

ProvideIMEI

Obtain_IMEI_MSC

Result=Pass?

Result:=Fail

Wait_For_TMSI_

Reallocation

Setup CheckIMEI

Check_IMEI_MSC

Result=Pass?

Wait_For_TMSI_

Reallocation

Abort

Map negative response toreject cause

CM ServiceReject

Result:=Fail

ForwardNew TMSI

ReallocateTMSI

Wait_For_TMSI_Ack

UseExistingTMSI

Result:=Pass

CM ServiceAccept

Startciphering

No

No

No

Yes

No

Yes

No

Yes

Yes

Figure 7b: Procedure Process_Access_Request_MSC (sheet 2)





Wait_For_TMSI_Ack

CMserviceabort

Abort

Result:=Fail

Setup Abort

Result:=Fail

TMSIReallocationFailure

ForwardNew TMSInegative response

Result:=Pass

TMSIReallocationComplete

ForwardNew TMSI ack

Figure 7c: Procedure Process_Access_Request_MSC (sheet 3)


Procedure in the MSCto determine the CLI presentation indicator value

Procedure Set_CLI_Presentation_Indicator_MSC CAIND_M1(1)

Signals to/from the rightare to/from the process CLIR_MAF004 Initiate

handlingof CLIR

Wait_For_CLIR_Info

Releasetransaction

From BSS Clearcall

Result:=Call notallowed

Continuecallhandling

Result:=Call

allowed

Figure 8: Procedure Set_CLI_Presentation_Indicator_MSC


Procedure in the MSCto determine the COLPinformation to be sent to the MS

Procedure Set_COLP_Info_MSC COINF_M1(1)

Signals to/from the rightare to/from the processCOLP_MAF006 Initiate

handlingof COLP

Wait_For_COLP_Info

Releasetransaction

From BSSContinuecallhandling

ReleaseFrom destinationexchange

Figure 9: Procedure Set_COLP_Info_MSC


Procedure in the MSCto handle AoC signalling towards the MS for an MO call

Procedure Handle_AoC_MO_MSC AoCMO_M1(1)

AoC(I)provisioned?

AoC(C)provisioned?

Acknowledgmentrequired:=

False

Setcharging

parameters

Acknowledgmentrequired:=

True

Setcharging

parameters

No

No

Yes

Yes

Figure 10: Procedure Handle_AoC_MO_MSC


Procedure in the MSCto obtain the IMSI from the MSand relay it to the VLR

Procedure Obtain_IMSI_MSC OIMSI_M1(1)

Signals to/from the left are to/from the BSS;Signals to/from the rightare to/from the VLR Send

IMSI

Wait_For_IMSI

Send IMSIack

ProvideIMSI ack

Result:=Pass

Releasetransaction

Abort

Result:=Aborted

Send IMSInegativeresponse

Releasetransaction

Figure 11: Procedure Obtain_IMSI_MSC


Procedure in the MSCto obtain the IMSI from the MSand relay it to the VLR

Procedure Authenticate_MSC AUT_MSC1(1)

Signals to/from the left are to/from the BSS;Signals to/from the rightare to/from the VLR Authenticate

Wait_For_Auth_Response

Authenticateack

Authenticateack

Wait_For_Auth_Result

Authenticationaccepted

Result:=Pass

Authenticationrejected


Releasetransaction

Abort

Result:=Aborted

Authenticatenegativeresponse

Releasetransaction

Figure 12: Procedure Authenticate_MSC


Procedure in the MSCto obtain the IMEI from the MSand relay it to the VLR

Procedure Obtain_IMEI_MSC OIMEI_M1(1)

Signals to/from the left are to/from the BSS;Signals to/from the rightare to/from the VLR Send

IMEI

Wait_For_IMEI

Send IMEIack

ProvideIMEI ack

Result:=Pass

Releasetransaction

Abort

Result:=Aborted

Send IMEInegativeresponse

Releasetransaction

Figure 13: Procedure Obtain_IMEI_MSC


Procedure in the MSC to check theIMEI and relay the result to the VLR

Procedure Check_IMEI_MSC CIMEI_M1(1)

Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR unless marked otherwise.

IMEIavailable?

Send IMEI

Wait_For_IMEI

CMserviceabort

Abort

Result:=Aborted

Send IMEInegativeresponse

Releasetransaction

Send IMEIack

Check IMEI To EIR

Wait_for_Check_IMEI_

Result

Releasetransaction

Abort

Result:=Aborted

Check IMEInegative response

From EIR

Check IMEInegative response

Result:=Pass

Check IMEIack

From EIR

Check IMEIack

No

Yes

Figure 14: Procedure Check_IMEI_MSC


7.1.2 Functional requirements of VLR

7.1.2.1 Process OCH_VLR

Sheet 2: it is an implementation option to carry out the check for operator determined barring of alloutgoing calls before the check on provisioning of the requested basic service.

Sheet 2: the negative response ‘call barred’ indicates whether the reason is operator determined barringor supplementary service barring, according to the result returned by the procedure Check_OG_Barring.

7.1.2.2 Procedure Process_Access_Request_VLR

Sheet 1: it is a network operator decision (subject to MoU requirements) how often an MS should beauthenticated.

Sheet 2: the processes Update_Location_VLR and Subscriber_Present_VLR are described in [17].

Sheet 2: it is a network operator decision (subject to MoU requirements) whether a connection should beciphered.

Sheet 3: it is a network operator decision (subject to MoU requirements) how often an IMEI should bechecked.

Sheet 5: it is a network operator decision whether emergency calls are allowed from an ME with no SIM.

7.1.2.3 Procedure Check_BAOC

Sheet 1: if the VLR receives an Abort message from the MSC while it is awaiting a response from theprocess MAF017, the message is saved for handling after return from the procedure.

7.1.2.4 Procedure OG_CUG_Check

If the VLR receives an Abort message from the MSC while it is awaiting a response from the processMAF014, the message is saved for handling after return from the procedure.

7.1.2.5 Procedure Check_OG_Barring

Sheet 2: if the VLR receives an Abort message from the MSC while it is awaiting a response from theprocess MAF018 or MAF019, the message is saved for handling after return from the procedure.

7.1.2.6 Procedure Get_LI_Subscription_Info_MO_VLR

If the VLR receives an Abort message from the MSC while it is awaiting a response from the processCLIR_MAF0003 or CLIR_MAF005, the message is saved for handling after return from the procedure.

7.1.2.7 Procedure Get_AoC_Subscription_Info_VLR

The indicator of whether or not AoC is provisioned is global data which can be read by the parent process.

7.1.2.8 Procedure Obtain_Identity_VLR

It is a network operator decision whether open (unciphered) identification of the MS by its IMSI is allowed.

7.1.2.9 Procedure Obtain_IMSI_VLR

7.1.2.10 Procedure Authenticate_VLR

Sheet 1: the number of unused authentication sets which triggers the VLR to request furtherauthentication sets from the HLR is an operator option.


7.1.2.11 Procedure Obtain_Authentication_Sets_VLR

7.1.2.12 Procedure Start_Tracing_VLR

7.1.2.13 Procedure Check_IMEI _VLR

If the response from the EIR to a request to check an IMEI is:

- blacklisted, then service is not granted;- greylisted, then service is granted, but the network operator may decide to initiate tracing;- whitelisted, then service is granted.

7.1.2.14 Procedure Obtain_IMEI _VLR

7.1.2.15 Process Fetch_Authentication_Sets_VLR


Process in the VLR to handle an outgoing (MO) call setup request

Process OCH_VLR OCH_VLR1(2)

Signals to/from the leftare to/from the MSC.

Idle


Process_Access_

Request_VLR

Result=Pass

Wait_For_SIFOC Idle

Yes

No

Figure 15a: Process OCH_VLR (sheet 1)


Process in the VLR to handle an outgoing (MO) call setup request

Process OCH_VLR OCH_VLR2(2)


Wait_For_SIFOC

Send Info For Outgoing Call

Emergencycall?

Basicservice

provisioned?

Check_BAOC

Callbarred?

OG_CUG_Check

Callallowed?

Check_OG_Barring

Callbarred?

Get_LI_Subscription_Info_MO_VLR

Get_AoC_Subscription_

Info_VLR

CompleteCall

Idle

Set negativeresponse:Call barred

Send Info For Outgoing Call negativeresponse

Idle

Set negativeresponse:

CUG reject



Basic servicenot provisioned

Bearer service or teleservice

Abort

Idle

No

Yes

No

Yes

No

Yes

No

Yes

No

Yes

Figure 15b: Process OCH_VLR (sheet 2)


Procedure in the VLRto handle a request from the MS for system access

Procedure Process_Access_Request_VLR PAR_VLR1(5)

Identityknown?

Obtain_Identity_VLR

Result=Pass?

Identity=IMEI?

Authenticationrequired?

IMSIdetached:=

False

Confirmed byRadio Contact:=

True

1

Authenticate_VLR

Result=Pass?

2

Set negativeresponse:SystemFailure

3

Result=Fail?


UnidentifiedSubscriber

3

Result:=Aborted

6

No

Yes

No

No

Yes

Yes

No

Yes

No

Yes

No

Yes

Figure 16a: Procedure Process_Access_Request_VLR (sheet 1)




1

Location infoconfirmed in HLR

Update_Location_VLR

Mobile NotReachable Flag set?

Subscriber_Present_VLR

Data confirmed by HLR



3

Roaming allowedin current LA?

Set negativeresponse:Roaming

Not Allowed

Tracingrequired?

Start_Tracing_VLR

Cipheringrequired?

4 5

False

Yes

False

True

No

Yes

Yes

Yes

No

No

No

True

Figure 16b: Procedure Process_Access_Request_VLR (sheet 2)




Signals to the leftare to the MSC.

4

SetCipheringMode

Identity:=IMSI


IMEI checkrequired?

Check_IMEI_VLR

Result=Pass?

TMSIreallocationrequired?

ForwardNew TMSI

FreezeexistingTMSI

Wait_For_TMSI_Ack

UseExistingTMSI

Result:=Pass

Result=Fail?

IMSIdetached:=

True


IllegalEquipment

3

Result:=Aborted

5

Yes

Yes

Yes

No

No

Yes

No

No

Figure 16c: Procedure Process_Access_Request_VLR (sheet 3)




Signals from the leftare from the MSC.

2

Result=Aborted?

Result:=Aborted

Result=Procedure

Error?


3

Result=Unknown

Subscriber?

Result=UnidentifiedSubscriber?




IllegalSubscriber

Wait_For_TMSI_Ack

ForwardNew TMSIack

UnfreezeexistingTMSI

Result:=Pass

ForwardNew TMSInegativeresponse

Yes

No

Yes

No

No

Yes

No

Yes

Figure 16d: Procedure Process_Access_Request_VLR (sheet 4)





3

CM service type=Emergency call?

Emergency callsetup allowedwithout SIM?

IMEIrequired?

Obtain_IMEI_VLR

Result=Pass?

Identity:=IMEI


Result:=Pass

Result=Fail?

Process AccessRequest negative response

Result:=Fail

Result:=Aborted

Yes

Yes

Yes

Yes

No

Yes

No

No

No

No

Figure 16e: Procedure Process_Access_Request_VLR (sheet 5)


Procedure to check callrequest against ODBAOCand SS BAOC

Procedure Check_BAOC CBAOC1(1)

Signals to/from the right are to/from the processMAF017

Operator determined BAOCimposed?

Result:=Call barred

(ODB)

Initiatehandlingof BAOC

Wait_For_BAOC_

Response

AbortContinuecallhandling

Callbarred?

Result:=Call barred(SS barring)

Result:=Call allowed

From MSC

Yes

No

Yes

No

Figure 17: Procedure Check_BAOC


Procedure to carry outCUG authorisation checkfor an outgoing (MO) call

Procedure OG_CUG_Check OG_CUG1(1)

Signals to/from the rightare to/from the processCUG_MAF014 outgoing

callrequest

Wait_For_CUG_Response

Abortrejectcall(cause)

Result:=Call barred

complete call(conditionalCUG info)


responseto callrequest

From MSC

Figure 18: Procedure OG_CUG_Check


Procedure to check callrequest against SS barringand ODB categories

Procedure Check_OG_Barring COB1(3)

Operator determinedBOIC imposed?

Destination address CC=Local CC?

1

Operator determinedBOIC-exHC imposed?


1

Destination address CC=HPLMN CC?

1

Operator determinedBOIZC imposed?

Destination address ZC=Local ZC?

1

Operator determinedBOIZC-exHC imposed?


1


Result:=Call barred

(ODB)

1

Yes

No

Yes

No

Yes

NoYes

No

Yes

No

Yes

No

Yes

No

Yes

NoYes

No

No

Yes

Figure 19a: Procedure Check_OG_Barring (sheet 1)



Procedure Check_OG_Barring COB2(3)

1

Operator determinedBOIC-exHC&BOIZCimposed?

2



2


Result:=Call barred

(ODB)

2

No

Yes

No

Yes

No

No

Yes

Yes

Figure 19b: Procedure Check_OG_Barring (sheet 2)



Procedure Check_OG_Barring COB3(3)2

Callbarred?

Initiatehandling of BOIC

To process MAF018

Wait_For_BOIC_

Response


From process MAF018

Callbarred?

Initiatehandling of BOIC-exHC

To process MAF020

Wait_For_BOIC-exHC_

Response


From process MAF020

Callbarred?



From MSC

From MSC

No

No

Yes

No

Yes

Yes

Figure 19c: Procedure Check_OG_Barring (sheet 3)


Procedure in the VLRto retrieve subscription information for the CLIR & COLP line identificationservices for an MO call

Procedure Get_LI_Subscription_Info_MO_VLR GLI_MOV1(1)

Initiatehandling of CLIR

Wait_For_CLIR_Info


Initiatehandling of COLP

Wait_For_COLP_Info


From process COLP_MAF005

To process COLP_MAF005

From process CLIR_MAF003

To process CLIR_MAF003

From MSC

From MSC

Figure 20: Procedure Get_LI_Subscription_Info_MO_VLR


Procedure in the VLR to determine the subscriptionto Advice of Charge services

Procedure Get_AoC_Subscription_Info_VLR GAOCI_V1(1)

AoC(I)provisioned?

AoC(C)provisioned?

Set indicator:AoC not

provisioned

Set indicator:AoC(C)

provisioned

Set indicator:AoC(I)

provisioned

No

No

Yes

Yes

Figure 21: Procedure Get_AoC_Subscription_Info_VLR


Procedure in the VLRto obtain the identity of an MS

Procedure Obtain_Identity_VLR OID_VLR1(1)

Identity=IMSI?

Identificationallowed?

Obtain_IMSI_VLR

Result=Pass?

IMSIknown?

Result:=Fail

Result:=Pass

Result:=Aborted

No

Yes

Yes

No

Yes

No

No

Yes

Figure 22: Procedure Obtain_Identity_VLR


Process in the VLRto obtain the IMSI from the MS via the MSC

Procedure Obtain_IMSI_VLR OIMSI_V1(1)


ProvideIMSI

Wait_For_IMSI

Abort

Result:=Aborted

ProvideIMSI ack

Result:=Pass

Figure 23: Procedure Obtain_IMSI_VLR


Procedure in the VLRto authenticate an MSvia the MSC

Procedure Authenticate_VLR AUT_VLR1(2)


Authenticationsets available?

Obtain_Authentication_

Sets_VLR

Result=Pass?

Result=Aborted?

Result:=Aborted

Result=Procedure

Error?

Result:=Procedure

Error

Result:=Unknown

Subscriber

Authenticate

Wait_For_Authenticate_

Result

Authenticateack

Received SRES=expected SRES?

Moreauthenticationsets needed?

Fetch_Authentication_

Sets_VLR


Result:=Pass

1

Abort

Moreauthenticationsets needed?


Sets_VLR

Result:=Aborted

2

No

No

Yes

No

Yes

No

Yes

Yes

Yes

No

No

Yes

No

Yes

Figure 24a: Procedure Authenticate_VLR (sheet 1)


Procedure in the VLRto authenticate an MSvia the MSC

Procedure Authenticate_VLR AUT_VLR2(2)


1

Identity=IMSI?

Retrywith

IMSI?

Obtain_IMSI_VLR

Result=Pass?

IMSIknown?

IMSImatchesTMSI?


Result:=Illegal

Subscriber

Identity:=IMSI

2


Result:=UnidentifiedSubscriber

Result:=Aborted

No

Yes

Yes

Yes

Yes

No

No

No

No

Yes

Figure 24b: Procedure Authenticate_VLR (sheet 2)


Procedure in the VLRto obtain authentication sets from the HLR

Procedure Obtain_Authentication_Sets_VLR OAS_VLR1(2)

Signals to/from the rightare to/from the HLR

SendAuthenticationInfo

Wait_For_Authentication_

Sets

SendAuthenticationInfo ack

Emptyresult?

Authenticationsets availablein VLR?

Re-useold

sets?

Result:=Pass

Result:=Procedure

Error

SendAuthenticationInfo negativeresponse

UnknownSubscriber?

Result:=Unknown

Subscriber

Yes

Yes

Yes No

No

No

No

Yes

Figure 25a: Procedure Obtain_Authentication_Sets_VLR (sheet 1)


Procedure in the VLRto obtain authentication sets from the HLR

Procedure Obtain_Authentication_Sets_VLR OAS_VLR2(2)

Signals to/from the left are to/from the MSC;Signals to/from the rightare to/from the HLR

Wait_For_Authentication_

Sets

Abort

Abort

Result:=Aborted

Abort

Authenticationsets available?

Re-useold

sets?

Result:=Pass

Result:=Procedure

Error

Yes

Yes No

No

Figure 25b: Procedure Obtain_Authentication_Sets_VLR (sheet 2)


Procedure in the VLRto request the MSC tostart activity tracing

Procedure Start_Tracing_VLR ST_TR_V1(1)

Signals to the left are to the MSC.

Tracingactive?

TraceSubscriberActivity

No

Yes

Figure 26: Procedure Start_Tracing_VLR


Procedure in the VLRto request the MSC tocheck an IMEI

Procedure Check_IMEI_VLR CIMEI_V1(1)

Signals to/from the leftare to/from the MSC

CheckIMEI

Wait_For_Check_IMEI_

Result

CheckIMEI ack

Servicegranted?

Result:=Fail

Result:=Pass

CheckIMEI negativeresponse

Abort

Result:=Aborted

No

Yes

Figure 27: Procedure Check_IMEI_VLR


Process in the VLRto obtain the IMSI from the MS via the MSC

Procedure Obtain_IMEI_VLR OIMEI_V1(1)


ProvideIMEI

Wait_For_IMEI

Abort

Result:=Aborted

ProvideIMEI ack

Result:=Pass

Figure 28: Procedure Obtain_IMEI _VLR


Process in the VLRto retrieve authenticationsets from the HLR

Process Fetch_Authentication_Sets_VLR FAS_VLR1(1)

Obiain_Authentication_

Sets_VLR

Figure 29: Process Fetch_Authentication_Sets_VLR


7.2 Retrieval of routeing information for MT call

7.2.1 Functional requirements of GMSC

7.2.1.1 Process MT_GMSC

Sheet 1: the suggested mapping from values of the Send Routeing Info negative response informationelement to values of the ISUP release cause (see [22]) is shown in table 1. The mapping used is a matterfor the network operator, depending on the telephony signalling system used.

Sheet 3: after the GMSC has sent an IAM to the destination VMSC or the forwarded-to exchange, it actsas a transparent relay for messages received from the originating exchange and the destination VMSC orthe forwarded-to exchange. Any message other than Address Complete, Connect, Answer or Releasecauses no change of state in the process MT_GMSC.

Table 1: Suggested mapping of Send Routeing Info (SRI) negative responses to ISUP releasecauses

SRI negative response ISUP release cause number ISUP release cause nameAbsent subscriber 20 Subscriber absentBearer service notprovisioned

57 Bearer capability not authorised

Call barred (ODB) 21 Call rejectedCall barred (SS barring) 21 Call rejectedCUG reject (Called party SSinteraction violation)

21 Call rejected

CUG reject (Incoming callsbarred within CUG)

55 Incoming calls barred within CUG

CUG reject (Subscriber notmember of CUG)

87 User not member of CUG

CUG reject (Requested basicservice violates CUGconstraints)

87 User not member of CUG

Data missing 111 Protocol error, unspecifiedFacility not supported 69 Requested facility not implementedForwarding violation 21 Call rejectedNumber changed 22 Number changedSystem failure 111 Protocol error, unspecifiedTeleservice not provisioned 57 Bearer capability not authorisedUnexpected data value 111 Protocol error, unspecifiedUnknown subscriber 1 Unallocated (unassigned) number

7.2.1.2 Procedure Handle_COLP_Forwarding_Interaction_MSC

The originating exchange or the destination exchange may release the call while a response is awaitedfrom the process COLP_MAF039. The message is saved for processing after return from the procedure.


Process in the GMSC tohandle a mobile-terminated call request

Process MT_GMSC MT_GMSC1(3)

Signals to/from the leftare to/from the originating exchange;signals to/from the rightare to/from the HLRunless otherwise marked

Idle

InitialAddress

From originatingexchange

SendRouteingInfo

Wait_For_Routeing_

Info

Release

Release callresources

Idle

SendRouteingInfo negativeresponse

Setcause

Release

SendRouteingInfo ack

Forwardingindicationreceived?

ConstructInitial

AddressMessage

InitialAddress

Towardsdestination MSC

Wait_For_ACM

Setredirectioninformation

InitialAddress

Towards destinationexchange

Wait_For_Forward_ACM

No

Yes

Figure 30a: Process MT_GMSC (sheet 1)




Signals to/from the left are to/from the originating exchange;signals to/from the right are to/from the destination exchange

Wait_For_ACM

AddressComplete

AddressComplete

Wait_For_Answer

Answer

Answer

Wait_For_Clear

Connect

Connect

Wait_For_Forward_ACM

AddressComplete

AddressComplete

Wait_For_Forward_Answer

Answer

Handle_COLP_Forwarding_

Interaction_MSC

Set COLPpresentation

indicator

Answer

Wait_For_Clear

Connect


Interaction_MSC


indicator

Connect

Figure 30b: Process MT_GMSC (sheet 2)




Signals to/from the left are to/from the originating exchange;signals to/from the right are to/from the destination exchange

Wait_For_ACM,Wait_For_Forward_ACM,Wait_For_Answer,Wait_For_Forward_Answer,Wait_For_Clear

Release

Release


Idle

Release

Release

Wait_For_ACM,Wait_For_Forward_ACM,Wait_For_Answer,Wait_For_Forward_Answer,Wait_For_Clear

*

-

-

*

-

Figure 30c: Process MT_GMSC (sheet 3)


Procedure in the GMSC or VMSCto handle the interaction betweenCOLP and Call Forwarding

Procedure Handle_COLP_Forwarding_Interaction_MSC COINT_M1(1)

Signals to/from the rightare to/from the processCOLP_MAF039 initiate

handlingof COLP

Wait_For_COLP_Info

Release From originating exchange or destination exchange

continuecallhandling

Figure 31: Procedure Handle_COLP_Forwarding_Interaction_MSC


7.2.2 Functional requirements of HLR

7.2.2.1 Process SRI_HLR

Sheet 1: The procedures Check_Parameters, Subscription_Check_HLR and First_Forwarding_HLR canset the negative response parameter which is used by the process SRI_HLR to construct the SendRouteing Info negative response message. This negative response parameter is global data, accessibleby the process SRI_HLR.

Sheet 2: The procedure PRN_Error_HLR can set the negative response parameter which is used by theprocess SRI_HLR to construct the Send Routeing Info negative response message. This negativeresponse parameter is global data, accessible by the process SRI_HLR.

7.2.2.2 Procedure Check_Parameters

If any parameters required by the rules in clause 8 are missing from the message, the procedure sets thenegative response to ‘Data missing. If any parameter has a value which is not in the set of valuesexpected for the parameter, the procedure sets the negative response to ‘Unexpected data value’.

7.2.2.3 Procedure Subscription_Check_HLR

It is an implementation option to carry out the check for operator determined barring of incoming callsbefore the check on provisioning of the requested basic service.

The negative response ‘Call barred’ indicates whether the reason is operator determined barring orsupplementary service barring, according to the result returned by the procedure Check_IC_Barring.

The negative response ‘CUG reject’ indicates whether the reason is:

- Incoming calls barred within CUG;- Requested basic service violates CUG constraints;- Subscriber not member of CUG

according to the cause returned by the procedure IC_CUG_Check.

7.2.2.4 Procedure First_Forwarding_HLR

7.2.2.5 Procedure PRN_Error_HLR

7.2.2.6 Procedure Forward_CUG_Check

7.2.2.7 Procedure Derive_Requested_Basic_Service_HLR

The rules for deriving a GSM bearer capability from ISDN compatibility information or the MSISDN of theB subscriber are specified in [18]. If a GSM bearer capability cannot be derived from the ISDNcompatibility information or the MSISDN of the B subscriber, the HLR applies a default basic serviceaccording to the requirements of the operator.

7.2.2.8 Procedure Check_IC_Barring

7.2.2.9 Procedure IC_CUG_Check

7.2.2.10 Procedure Handle_CFU

The test ‘Normal call’ refers to the value of the indicator returned by the process MAF007.

7.2.2.11 Procedure Handle_CFNRc

The test ‘Mobile subscriber not reachable’ refers to the value of the indicator returned by the processMAF010.


Process in the HLR to handle a request for routeing information

Process SRI_HLR SRI_HLR1(2)

Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the VLR

Idle

SendRouteingInfo

Check_Parameters

Result=Pass?

Subscription_Check_HLR

Result=Fail?

First_Forwarding_

HLR

Result=Fail?

Result=Forward?

GSM BC=NULL?

SetGSM BC

parameter

ProvideRoamingNumber

Wait_For_MSRN

2 1

Yes

No

No

No

No

Yes

Yes

Yes

Yes

No

Figure 32a: Process SRI_HLR (sheet 1)


Process in the HLR to handle a request for routeing information

Process SRI_HLR SRI_HLR2(2)

Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the VLR

Wait_For_MSRN

ProvideRoamingNumber ack

Routeingaddress:=

MSRN


Idle

Provide RoamingNumber negativeresponse

PRN_Error_HLR

Result=Fail?

Send RouteingInfo negativeresponse

Idle

Forward_CUG_Check

Callallowed?

Routeingaddress:=

FTN


Idle


CUG reject

Called party SSinteractionviolation

1

2

Yes

No

Yes

No

Figure 32b: Process SRI_HLR (sheet 2)


Procedure to checkthe parameters of areceived message

Procedure Check_Parameters Chk_Par1(1)

All requiredparameters present?

All parameter values acceptable?


Unexpecteddata value

Result:=Fail

Result:=Pass


Data missing

Yes

No

Yes

No

Figure 33: Procedure Check_Parameters


Procedure in the HLRto make subscriptionchecks for a mobile-terminated call

Procedure Subscription_Check_HLR SC_HLR1(1)

MSknown?

Set negativeresponse:Unknownsubscriber

Result:=Fail

Numberchanged?

Set negativeresponse:Number changed

Derive_Requested_Basic_Service_HLR

Requestedservice

provisioned?

Set negativeresponse:service notprovisioned

Bearer serviceorTeleservice

Check_IC_Barring

Callbarred?


IC_CUG_Check

Callallowed?


CUG reject

Result:=Pass

No

Yes

Yes

No

No

Yes

Yes

No

No

Yes

Figure 34: Procedure Subscription_Check_HLR


Procedure in the HLRto handle call forwardingbefore interrogation of the VLR

Procedure First_Forwarding_HLR FF_HLR1(1)

Handle_CFU

Result=Fail?

Result=Forward?

Result:=Forward

MS notreachable?

Result:=Continue

Handle_CFNRc

Result=Fail?

Result=Forward?

Result:=Forward


Absentsubscriber

Result:=Fail


Forwardingviolation


Forwardingviolation

No

Yes

No

No

Yes

No

Yes

No

Yes

Yes

Figure 35: Procedure First_Forwarding_HLR


Procedure in the HLRto handle a negative responsefor a roaming number request

Procedure PRN_Error_HLR PRN_E_H1(1)

Handle_CFNRc

Result=Fail?


Forwardingviolation

Result:=Fail

Result=Forward?


Absentsubscriber

Result:=Forward

Negativeresponse=Absentsubscriber?

Handle_CFNRc

Result=Fail?

Result=Forward?

Set negativeresponse:System failure

Result:=Fail


Forwardingviolation

Set negativeresponse:System failure

Negativeresponse=No roamingnumber?

Set negativeresponse:Facility notsupported

Negativeresponse=Facilitynot supported?

No

Yes

Yes

No

No

Yes

No

Yes

No

Yes

No

Yes

No

Yes

Figure 36: Procedure PRN_Error_HLR


Procedure to carry outCUG authorisation checkfor a forwarded call

Procedure Forward_CUG_Check FWD_CUG1(1)

PerformForwarding CUG

authorisation

CUGauthorisation

result

Result:=Call barred


Update CUGinfo As defined in GSM 03.85

As defined in GSM 03.85


CUG info provided in routeing informationrequest

CUG provisioned forforwarding subscriber against requested basic service

Yes

Fail

Pass

No

No

Yes

Figure 37: Procedure Forward _CUG_Check


Procedure in the HLR to derive the requested basic service for an incoming (MT) call according to the rules of GSM 09.07

Procedure Derive_Requested_Basic_Service_HLR DRBS_H1(1)

ExhaustiveISDN compatibility information available?

Multi-numbering?

GSM BC:=NULL

Basic service:=default

Apply GSM BCfor this

MSISDN

Derive basicservice from

GSM BC

Derive GSM BC fromISDN compatibility

information

No

No

Yes

Yes

Figure 38: Procedure Derive_Requested_Basic_Service_HLR


Procedure to check callrequest against SS barring and ODB categories

Procedure Check_IC_Barring CIB1(2)

1

Result:=Call barred

(ODB)

MS registeredin HPLMNzone?

Operator determinedBIC-RoamHZimposed?

1

MS registeredin HPLMNcountry?

Operator determinedBIC-Roam imposed?

Operator determinedBAIC imposed?

No

No

No

Yes

Yes

No

Yes

No

Yes

Yes

Figure 39a: Procedure Check_IC_Barring (sheet 1)


Procedure to check callrequest against SS barring and ODB categories

Procedure Check_IC_Barring CIB2(2)

1

Initiatehandling of BAIC

Wait_For_BAIC_

Response


Callbarred?

Initiatehandling of BIC-Roam

Wait_For_BIC-Roam_Response


Callbarred?



From process MAF023

To process MAF023

From process MAF022

To process MAF022

No

Yes

No

Yes

Figure 39b: Procedure Check_IC_Barring (sheet 2)


Procedure to carry outCUG authorisation checkfor an incoming (MT) call

Procedure IC_CUG_Check IC_CUG1(1)

Signals to/from the rightare to/from the processCUG_MAF015

incomingcall

Wait_For_CUG_Response

rejectcall(cause)

Result:=Call barred

(cause)

complete call(conditionalCUG info)


responseto callrequest

To processCUG_MAF015

Figure 40: Procedure IC_CUG_Check


Procedure in the HLRto handle Call ForwardingUnconditional

Procedure Handle_CFU H_CFU1(1)

Signals to/from the rightare to/from the processMAF007 initiate

handlingof CFU

Wait_For_CFU_Result


Error?

Normalcall?

Result:=Forward

Result:=Continue

Result:=Fail

No

No

Yes

Yes

Figure 41: Procedure Handle_CFU


Procedure in the HLRor VLR to handle CallForwarding on Mobile Subscriber Not Reachable

Procedure Handle_CFNRc H_CFNRc1(1)


handlingof CFNRc

Wait_For_CFNRc_Result


Error?

Mobile subscribernot reachable?

Result:=Forward

Result:=Continue

Result:=Fail

No

No

Yes

Yes

Figure 42: Procedure Handle_CFNRc



7.2.3.1 Process PRN_VLR

Sheet 1: the procedure Check_Parameters is specified in subclause 7.2.2.2.

Sheet 2: the number of unused authentication sets which triggers the VLR to request furtherauthentication sets from the HLR is an operator option.

Sheet 2: the process Fetch_Authentication_Sets_VLR is specified in subclause 7.1.2.15.

7.2.3.2 Process Restore_Subscriber_Data_VLR

7.2.3.3 Process PSI_VLR

Sheet 1: the procedure Check_Parameters is specified in subclause 7.2.2.2.

Sheet 2: the task 'Set Location Info' encompasses:

- Insertion of the cell ID if it was received from the MSC, otherwise retrieval of the stored locationarea ID;

- Derivation of the location number and geographical infornmation from the cell ID or location area IDif the VLR is capable of doing so;

- Insertion of the age of the location information received from the MSC;- Insertion of the VLR number.

Sheet 2: the task ‘Set subscriber state’ consists of inserting the subscriber state if it was received from theMSC, otherwise inserting the state ‘Network determined not reachable’.


Process in the VLR to handlea request for a roaming number

Process PRN_VLR PRN_VLR1(3)

Signals to/from the left are to/from the HLR.

Idle

ProvideRoamingNumber

Check_Parameters

Result=Pass?

ORindicatorpresent?

ORsupported?

Convert GSM BCto basic service

If GSM BC was includedin the Provide Roaming Number

Servicesupportedby VLR?

IMSIknown in VLR?

2 IMSIdetached?

Roamingin LA

allowed?


Absentsubscriber

13


Facilitynot supported


OR notallowed

Yes

Yes

Yes

Yes

No

Yes

No

No

Yes

Yes

No

No

No

No

Figure 43a: Process PRN_VLR (sheet 1)




Signals to the left are to the HLR.

2

MSRNavailable

AllocateMSRN

CreateIMSI

record

Dataconfirmed by HLR:=

False

Confirmedby radio

contact:=False

Location infoconfirmedin HLR:=

False

Only if >1 MSCper VLR

IMSIdetached:=

False

Allocate LMSIIf usedby VLR

Storecompatibility

info

GSM BC, ISDN BC,ISDN LLC & ISDN HLC(as available)



Sets_VLR

Restore_Subscriber_Data_VLR

Idle


No roamingnumber

Provide RoamingNumbernegative response

Idle

1

4

Moreauthentication sets needed?

Yes

No

Yes

No

Figure 43b: Process PRN_VLR (sheet 2)




Signals to the left are to the HLR.

3

MSRNavailable

MSCper VLR

Received MSC number=Stored MSC number

Confirmed byradio contact

Use receivedMSC number

for MSRN

AllocateMSRN

Storecompatibility

info

GSM BC, ISDN BC,ISDN LLC & ISDN HLC(as available)


Dataconfirmed

by HLR

Idle 4

Use storedMSC number

for MSRN


No roamingnumber

Provide RoamingNumbernegative response

Idle

Yes

>1

No

False

True

False

True

Yes

1

No

Figure 43c: Process PRN_VLR (sheet 3)


Process in the VLRto restore subscriber data

Process Restore_Subscriber_Data_VLR RSD_VLR1(1)

Signals to/from the leftare to/from the HLR

RestoreData

Wait_For_Data

RestoreData ack

UpdateSubscriber

Data

UpdateHLR

number

Update MSNot Reachable

indicator

If receivedfrom HLR

Data confirmed by HLR:=True

RestoreData negativeresponse

Figure 44: Process Restore_Subscriber_Data_VLR


Process in the VLR to handlea request from the HLR forsubscriber information

Process PSI_VLR PSI_VLR1(2)

Signals to/from the leftare to/from the HLR; signals to/from the rightare to/from the MSC

Idle

ProvideSubscriberInfo

Check_Parameters

Result=Pass?

IMSIknown

in VLR?

Subscriberstate

requested?

IMSIdetached?

Roamingin LA

allowed?

Set subscriberstate

requested

Location info

requested?

Set subscriberstate

requested

ObtainSubscriberInfo

Wait_For_MSC_Response

Subscriber atate:=Network determined

not reachable

Location info

requested?

ProvideSubscriberInfo ack

Idle

Subscriberstate

requested?

Subscriber state:=Assumed idle

ProvideSubscriberInfo negativeresponse

Idle

Yes

Yes

Yes

No

Yes

Yes

No

Yes

No

Yes

No

No

Yes

No

No

Figure 45a: Process PSI_VLR (sheet 1)


Process in the VLR to handlea request from the HLR forsubscriber information

Process PSI_VLR PSI_VLR2(2)

Signals to/from the leftare to/from the HLR; signals to/from the rightare to/from the MSC

Wait_For_MSC_Response

ObtainSubscriberInfo ack

Locationinfo

received?

Setlocation

info

Subscriberstate

received?

Setsubscriber

state

ProvideSubscriberInfo ack

Idle

Yes

Yes

No

No

Figure 45b: Process PSI_VLR (sheet 2)


7.2.4 Functional requirements of MSC

7.2.4.1 Process OSI_MSC

If the MS is engaged on a circuit-switched call, the state is busy, otherwise assumed idle.


Process in the MSC to handlea request from the VLR forinformation on the subscriber's location and state

Process OSI_MSC OSI_MSC1(1)

Signals to/from the leftare to/from the VLR

Idle

ObtainSubscriberInfo

Locationinfo

requested?

Set age of location info

MS inradio

contact?

Set cellglobalidentity

Subscriberstate

requested?

Setsubscriber

state

ObtainSubscriberInfo ack

Idle

Yes

Yes

Yes

No

No

No

Figure 46: Process OSI_MSC


7.3 MT call

7.3.1 Functional requirements of serving MSC

7.3.1.1 Process ICH_MSC

Sheet 1: the rules for converting the ISDN BC/LLC/HLC to a GSM bearer service or teleservice arespecified in [18].

Sheet 1: the procedure Process_Access_Request_MSC is specified in subclause 7.1.1.2.

Sheet 2: the suggested mapping from values of the Send Info For Incoming Call negative responseinformation element to values of the ISUP release cause (see [22]) is shown in table 2. The mapping usedis a matter for the network operator, depending on the telephony signalling system used.

Table 2: Suggested mapping of Send Info For Incoming Call (SIFIC) negative responses to ISUPrelease causes

SIFIC negative response ISUP release cause number ISUP release cause nameAbsent subscriber 20 Subscriber absentBusy subscriber 17 User busyCUG reject (Called party SSinteraction violation)

21 Call rejected

Forwarding violation 21 Call rejectedImpossible call completion 111 Protocol error, unspecifiedNo subscriber reply 19 No answer from user (user alerted)System failure 111 Protocol error, unspecifiedUnallocated roaming number 111 Protocol error, unspecified

Sheet 3: the procedure Handle_COLP_Forwarding_Interaction is specified in subclause 7.2.1.2.

Sheet 5: after the VMSC has sent an IAM to the forwarded-to exchange, it acts as a transparent relay formessages received from the GMSC and the forwarded-to exchange. Any message other than AddressComplete, Connect, Answer or Release causes no change of state in the process ICH_MSC.

7.3.1.2 Procedure Page_MS_MSC

Sheet 1: For an SMS or SS page, the test 'Call still exists' takes the 'Yes' exit if the SMS or SS transactionwhich led to the page still exists.

Sheet 1: the test ‘SMS or SS page’ is not required for the handling of circuit-switched calls, because theVLR will always use a page type of ‘circuit-switched call’, but the more generalised procedurePage_MS_MSC is equally applicable to paging for SMS delivery or network-initiated SS procedures.

Sheet 1: the test ‘MS busy’ takes the ‘Yes’ exit if the MS is engaged on a circuit-switched call.

Sheet 1: the test ‘Call in setup’ takes the ‘Yes’ exit if the call on which the MS is engaged has not reachedthe established phase (called party answer).

Sheet 1: the test Call waiting’ takes the ‘Yes’ exit if a waiting call has been offered to the subscriber butthe outcome of offering the call has not been determined.

Sheet 1: the negative response Busy Subscriber (More calls possible) includes the basic service whichapplies for the established call.

Sheet 2: the signal input ‘MS connection established’ indicates that the MS has responded to paging, orsent a CM sevice request for anything other than a circuit-switched call, or completed the locationregistration procedure.


7.3.1.3 Procedure Search_For_MS_MSC

Sheet 1: For an SMS or SS page, the test 'Call still exists' takes the 'Yes' exit if the SMS or SS transactionwhich led to the page still exists.

Sheet 1: the test ‘SMS or SS page’ is not required for the handling of circuit-switched calls, because theVLR will always use a page type of ‘circuit-switched call’, but the more generalised procedureSearch_For_MS_MSC is equally applicable to paging for SMS delivery or network-initiated SSprocedures.

Sheet 1: the test ‘MS busy’ takes the ‘Yes’ exit if the MS is engaged on a circuit-switched call.

Sheet 1: the test ‘Call in setup’ takes the ‘Yes’ exit if the call on which the MS is engaged has not reachedthe established phase (called party answer).

Sheet 1: the test Call waiting’ takes the ‘Yes’ exit if a waiting call has been offered to the subscriber butthe outcome of offering the call has not been determined.

Sheet 1: the negative response Busy Subscriber (More calls possible) includes the basic service whichapplies for the established call.

Sheet 2: the signal input ‘MS connection established’ indicates that the MS has responded to paging, orsent a CM sevice request for anything other than a circuit-switched call, or completed the locationregistration procedure.

7.3.1.4 Procedure Complete_Call_In_MSC

Sheet 1: the MSC and the MS may negotiate the bearer capability to be used for the call by the exchangeof information in the Setup and Call Confirmed messages.

7.3.1.5 Procedure Process_Call_Waiting_MSC

Sheet 1: the MSC and the MS may negotiate the bearer capability to be used for the call by the exchangeof information in the Setup and Call Confirmed messages.

Sheet 1: the Call Confirmed message indicates 'busy' for the successful case.

Sheets 1 & 2: the Release transaction (reject) message covers all unsuccessful cases not otherwiseindicated.

7.3.1.6 Procedure Set_CLIP_Info_MSC

The originating exchange may release the call or the MS may terminate the transaction with the networkby sending a Release transaction message while a response is awaited from the process CLIP_MAF002.The message is saved for processing after return from the procedure.

7.3.1.7 Procedure Derive_GSM_BC_MSC

7.3.1.8 Procedure Handle_AoC_MT_MSC

7.3.1.9 Procedure Set_COL_Presentation_Indicator_MSC

The originating exchange may release the call or the MS may terminate the transaction with the networkby sending a Release transaction message while a response is awaited from the process COLP_MAF041.The message is saved for processing after return from the procedure.


Process in the MSCto handle an incoming (MT) call

Process ICH_MSC ICH_MSC1(5)

Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise

Idle

InitialAddress From GMSC

Convert ISDN BC/LLC/HLC(if present) to GSM bearer service/teleservice& GSM BC

Send InfoFor IncomingCall

Wait_For_Page_Request

Send InfoFor IncomingCall negativeresponse

Setcause

Release To GMSC


Idle

Page MS

Page_MS_MSC

Result=Pass?

Process_Access_

Request_MSC

Result=Pass?

Wait_For_MT_Call_

Result

Release To GMSC


Idle

Result=Fail?


Idle

Wait_For_MT_Call_

Result

SearchFor MS

Search_For_MS_MSC

Result=Pass?

Result=Fail

Wait_For_MT_Call_

Result


Idle

Yes

Yes

No

No

No

Yes

Yes

No

Yes

No

Figure 47a: Process ICH_MSC (sheet 1)





Wait_For_MT_Call_

Result


Set cause

ReleaseTo GMSC

Releasetransaction

Release call

resources

Idle

CompleteCall

Complete_Call_In_MSC

Result=Pass?

Result=Fail

Wait_For_MT_Call_

Result

Send InfoFor IncomingCall ack

Call is to beforwarded

Set redirectioninformation

Addresscomplete

InitialAddressMessage

Towards exchange defined byforwarded-to number

Wait_For_ACM

Release call

resources

Idle

Wait_For_Clear

ProcessCallWaiting

Process_Call_

Waiting_MSC

Result=Pass?

Result=Fail

Release call

resources

Idle

Wait_For_Clear

No

Yes

No

Yes

No

Yes

No

Yes

Figure 47b: Process ICH_MSC (sheet 2)




Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the destination exchange

Wait_For_ACM

Release Release AddressComplete

Connect

Release ReleaseAddressComplete


Start Answerguard timer

Idle Wait_For_Answer

Release Release Answer

Release ReleaseHandle_COLP_

Forwarding_Interaction_MSC


Interaction_MSC



indicator


indicator

Idle Answer Connect

Wait_For_Forwarded_Clear

Figure 47c: Process ICH_MSC (sheet 3)




Signals to/from the leftare to/from the BSS;signals to/from the rightare to/from the VLRunless otherwise indicated

Wait_For_MT_Call_Result,Wait_For_Clear

Releasetransaction

Release To GMSC

Abort

Releasecall

resources

Idle

Release From GMSC

Releasetransaction

Wait_For_Forwarded_Clear

Release From GMSC

ReleaseTowards destinationexchange

Releasecall

resources

Idle

Release From destinationexchange

Release To GMSC

Figure 47d: Process ICH_MSC (sheet 4)




Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the destination exchange

Wait_For_ACM,Wait_For_Answer,Wait_For_Forwarded_Clear

*

-

-

*

-

Figure 47e: Process ICH_MSC (sheet 5)


Procedure in the MSCto page an MS in aspecified location area

Procedure Page_MS_MSC PAGE_M1(2)


Locationarea IDknown?


Unknown LAI

Page MSnegativeresponse

Result:=Fail

Callstill

exists?


MSconnection

exists?

SMS or SSpage?

MS busy?

Call insetup?

Callwaiting?


Busy Subscriber

More callspossible


Busy Subscriber(NDUB)

Set accessconnection

status

Result:=Pass

Clear received:=False

PageIn specified location area

Start Pageresponse

timer

Wait_For_Page_

Response

No

Yes

No

Yes

Yes

No

Yes

No

No

Yes

Yes

No

Yes

No

Figure 48a: Procedure Page_MS_MSC (sheet 1)


Procedure in the MSCto page an MS in aspecified location area

Procedure Page_MS_MSC PAGE_M2(2)


Wait_For_Page_

Response

MSconnectionestablished

Clearreceived


status

Result:=Pass

Releasetransaction

Result:=Aborted

Release From GMSC

Abort

Clear received:=True

Wait_For_Page_

Response

Pageresponsetimer expired

Clearreceived


AbsentSubscriber


Result:=Fail

Result:=Aborted

CM ServiceRequest

For circuit-switched call

CM ServiceRequest

To process OCH_MSC

Clearreceived




Result:=Fail

Result:=Aborted

False

True

False

True

False

True

Figure 48b: Procedure Page_MS_MSC (sheet 2)


Procedure in the MSCto search for an MS (page in all location areas)

Procedure Search_For_MS_MSC SRCH_M1(2)


Callstill

exists?

MSconnection

exists?

SMS or SSpage?

MS busy?

Call insetup?

Callwaiting?


Busy Subscriber

More callspossible

SearchFor MSnegativeresponse

Result:=Fail




status

Result:=Pass

Clear received:=False

PageIn alllocation areas

Start Pageresponse

timer

Wait_For_Search_

Response


Yes

Yes

No

Yes

No

No

Yes

Yes

No

Yes

No

No

Figure 49a: Procedure Search_For_MS_MSC (sheet 1)


Procedure in the MSCto search for an MS (page in all location areas)

Procedure Search_For_MS_MSC SRCH_M2(2)


Wait_For_Search_

Response

MSconnectionestablished

Clearreceived

Search For MS ack


status

Result:=Pass

Releasetransaction

Result:=Aborted

Release From GMSC

Abort

Clear received:=True

Wait_For_Search_

Response

Pageresponsetimer expired

Clearreceived


AbsentSubscriber

Search For MS negativeresponse

Result:=Fail

Result:=Aborted

CM ServiceRequest

For circuit-switched call

CM ServiceRequest

To process OCH_MSC

Clearreceived



Search For MS negativeresponse

Result:=Fail

Result:=Aborted

False

True

False

True

False

True

Figure 49b: Procedure Search_For_MS_MSC (sheet 2)


Procedure in the MSCto complete an MT call on request from the VLR

Procedure Complete_Call_In_MSC CCI_MSC1(4)


Set_CLIP_Info_MSC

Setup

Wait_For_Setup_

Response

CallConfirmed

Allocatechannel


Setup failure


AbsentSubscriber

CompleteCallnegativeresponse

Result:=Fail

Derive_GSM_BC_

MSC

Figure 50a: Procedure Complete_Call_In_MSC (sheet 1)






AllocationComplete

Wait_For_Alerting

Alerting

NRCTprovided?

Start No ReplyCall Timer

AddressComplete To GMSC

Wait_for_Answer

Connect

Handle_AoC_MT_MSC

Result=Pass?

Connectack

Set_COL_Presentation_Indicator_MSC

ConnectTo GMSC

CompleteCallack

Result:=Pass

Release To GMSC

Abort

Result:=Aborted

Alertingfailure

Abort

Release To GMSC

Result:=Aborted

Allocationfailure


Radiocongestion


Result:=Fail

Yes

No

Yes

No

Figure 50b: Procedure Complete_Call_In_MSC (sheet 2)





Wait_for_Answer

No ReplyCall Timerexpired


No subscriberreply


Result:=Fail

Connect

Handle_AoC_MT_MSC

Result=Pass?

Connectack


Answer To GMSC

CompleteCallack

Result:=Pass

Release To GMSC

Abort

Result:=Aborted

Yes

No

Figure 50c: Procedure Complete_Call_In_MSC (sheet 3)





Wait_For_Setup_Response,Wait_For_Assignment_Complete,Wait_For_Alerting,Wait_For_Answer

Releasetransaction

Userbusy?


Busy subscriber(UDUB)


Result:=Fail

Release To GMSC

Abort

Releasecall

resources

Result:=Aborted

Release From GMSC

Releasetransaction

Yes

No

Figure 50d: Procedure Complete_Call_In_MSC (sheet 4)


Procedure in the MSCto handle a Process Call Waitingrequest from the VLR

Procedure Process_Call_Waiting_MSC PCW_MSC1(3)


Call beingset up


Busysubscriber

ProcessCall Waitingnegativeresponse

Result:=Fail

Set_CLIP_Info_MSC

Setup

Wait_For_Setup_

Response

CallConfirmed

Wait_For_Alerting

Alerting

NRCTprovided?

StartNo ReplyCall Timer

AddressComplete

To GMSC ofwaiting call

Wait_For_Acceptance

StartAcceptance

timer

Alertingfailure

Abort

ReleaseTo GMSC ofwaiting call

Result:=Aborted

Releasetransaction(UDUB)


Busysubscriber


Result:=Fail

Releasetransaction(reject)

Release To GMSC ofwaiting call

Abort

Result:=Aborted

Setup failure

Clearpendingcall

Derive_GSM_BC_

MSC

Yes

No

Yes

No

Figure 51a: Procedure Process_Call_Waiting_MSC (sheet 1)





Wait_for_Acceptance

Connect

Assignmentrequired?

Allocate channel


AllocationComplete

Handle_AoC_MT_MSC

Result=Pass?

Connectack


Answer To GMSC ofwaiting call

Process CallWaiting ack

Result:=Pass


Abort

Result:=Aborted

Allocationfailure

Yes

Yes

No

No

Figure 51b: Procedure Process_Call_Waiting_MSC(sheet 2)





Wait_for_Acceptance

Releasetransaction(busy)


Busysubscriber


Result:=Fail

Releasetransaction(reject)


Abort

Result:=Aborted

Acceptance timer expired

Clearpendingcall

No ReplyCall Timerexpired


No subscriberreply


Result:=Fail

Wait_For_Setup_Response,Wait_For_Assignment_Complete,Wait_For_Alerting,Wait_For_Acceptance

Release From GMSC ofwaiting call

Clearpendingcall

Abort

Result:=Aborted

Figure 51c: Procedure Process_Call_Waiting_MSC(sheet 3)


Procedure in the MSCto determine the CLIPinformation to be sent to the MS

Procedure Set_CLIP_Info_MSC CAINF_M1(1)

Signals to/from the rightare to/from the processCLIP_MAF002 Initiate

handlingof CLIP

Wait_For_CLIP_Info

Releasetransaction


Release From GMSC

Figure 52: Procedure Set_CLIP_Info_MSC


Procedure in the MSC toderive the requested GSM BCfor an incoming (MT) call according to the rules ofGSM 09.07

Procedure Derive_GSM_BC_MSC DRBC_M1(1)

GSM BC derived from ISDN compatibility information?

Use GSM BCderived from

ISDN compatibilityinformation

GSM BC receivedin PRN?

Omit GSM BCfrom Setup

Use GSM BCreceived in PRN

Yes

No

No

Yes

Figure 53: Derive_GSM_BC_MSC


Procedure in the MSCto handle AoC signalling towards the MS for an MT call

Procedure Handle_AoC_MT_MSC AOCMT_M1(1)

Signals to/from the leftare to/from the BSS;signals from the rightare from the AoC timer function.

AoC(I)provisioned?

Setcharging

parameters

SendChargingParameters

Result:=Pass

AoC(C)provisioned?

Setcharging

parameters

SendChargingParameters

Start AoCacknowledgment

timer

Wait_For_Charging_

Parameters_Ack

Charging Parametersack

Releaseconnection

Result:=Fail

AoCacknowledgmenttimer expired

Releasetransaction

Yes

No

No

Yes

Figure 54: Procedure Handle_AoC_MT_MSC


Procedure in the MSCto determine the COL presentation indicator value

Procedure Set_COL_Presentation_Indicator_MSC COIND_M1(1)

Signals to/from the rightare to/from the processCOLR_MAF041 Initiate

handlingof COLR

Wait_For_COLR_Info

Releasetransaction


Release From GMSC

Figure 55: Procedure Set_COL_Presentation_Indicator MSC



7.3.2.1 Process ICH_VLR

Sheet 1: if the MSRN received in the Send Info For Incoming Call is not allocated or there is no IMSIrecord for the IMSI identified by the MSRN, this is treated as an unknown MSRN.

Sheet 2: the procedure Process_Access_Request_VLR is specified in subclause 7.1.2.2.

Sheet 2: the test 'NDUB?' takes the 'Yes' exit if the Page MS negative response or the Search for MSnegative response had the value Busy Subscriber (NDUB).

Sheet 2: the VLR uses the basic service returned in the Page MS negative response or the Search for MSnegative response Busy Subscriber (More calls possible) to determine whether call waiting is available.

Sheet 2: the procedure Get_AoC_Subscription_Info_VLR is specified in subclause 7.1.2.7.

Sheet 5: the procedure Handle_CFNRc is specified in subclause 7.2.2.11.

Sheet 6: the procedure Forward_CUG_Check is specified in subclause 7.2.2.6.

7.3.2.2 Procedure Derive_Requested_Basic_Service_VLR

If the VLR did not receive a basic service for the call in the Send Info For Incoming Call, and did notreceive a GSM bearer capability in the Provide Roaming Number, it applies a default basic serviceaccording to the requirements of the operator.

7.3.2.3 Procedure Search_For_MS_VLR

7.3.2.4 Procedure Get_CW_Subscription_Info_VLR

The MSC may abort the transaction with the VLR while a response is awaited from the process MAF013.The message is saved for processing after return from the procedure.

7.3.2.5 Procedure Get_LI_Subscription_Info_MT_VLR

The MSC may abort the transaction with the VLR while a response is awaited from the processCLIP_MAF001 or the process COLR_MAF040. The message is saved for processing after return from theprocedure.

7.3.2.6 Procedure Handle_CFB

The test ‘Normal call busy’ refers to the value of the indicator returned by the process MAF008.

7.3.2.7 Procedure Handle_CFNRy

The test ‘Normal call’ refers to the value of the indicator returned by the process MAF009.


Process in VLRB tohandle a request for informationfor an incoming (MT) call

Process ICH_VLR ICH_VLR1(6)


Idle

Send InfoFor IncomingCall

MSRNknown?

Dataconfirmed

by HLR



Idle

Derive_Requested_Basic_Service_VLR

IMSIdetached?

Roamingin LA

allowed?

Locationarea IDknown?

Search_For_MS_VLR

Result=Pass?

Result=Fail?

Idle 2Wait_For_Access_Request

Page MS Page type=circuit-switched call

1


UnallocatedRoaming Number

Yes

False

True

No

Yes

No

No

No

Yes

Yes

Yes

No

Yes

No

Figure 56a: Process ICH_VLR (sheet 1)





Wait_For_Access_Request


Absentsubscriber?

1

Busysubscriber?

3

NDUB?

Get_CW_Subscription_

Info_VLR

CWavailable?

Get_LI_Subscription_Info_MT_VLR


Info_VLR

4 5


Process_Access_

Request_VLR

Result=Pass?

CUGinfo

present?

Translate CUGinterlockto index

As defined in GSM 03.85

Success?

CFNRyA&O?

ProvideNRCTvalue

Get_LI_Subscription_Info_MT_VLR


Info_VLR

CompleteCall

Wait_For_Complete_Call_

Result


System failure


Idle

Idle

Abort2

3

Yes

No

No

Yes

No

Yes

No

Yes

Yes

Yes

Yes

Yes

No

No

No

No

Figure 56b: Process ICH_VLR (sheet 2)





Wait_for_Complete_Call

Result

CompleteCall ack

Idle

AbortCompleteCall negativeresponse

Busysubscriber?

Absentsubscriber?

Radiocongestion?

Nosubscriber

reply?


Impossible callcompletion


Idle 6 1 5

No

No

No

No

Yes

Yes

Yes

Yes

Figure 56c: Process ICH_VLR (sheet 3)





4

CFNRyA&O?

Set NRCT

ProcessCallWaiting

Wait_For_PCW_Result

ProcessCallWaiting ack

Idle

Abort

ProcessCall Waiting negativeresponse

Busysubscriber?

Nosubscriber

reply?


Impossible callcompletion


Idle 6 5

Yea

No

No

Yes

Yes

No

Figure 56d: Process ICH_VLR (sheet 4)




1

Handle_CFNRc

Result=Fail?


ForwardingViolation


Idle

Result=Forward?


AbsentSubscriber

7

5

Handle_CFB

Result=Fail?


ForwardingViolation

Result=Forward?


Busy Subscriber

7

6

Handle_CFNRy

Result=Fail?


ForwardingViolation

Result=Forward?


No SubscriberReply

7

Yes

No

No

YesYes

No

No

Yes

Yes

No

No

Yes

Figure 56e: Process ICH_VLR (sheet 5)





7

Forward_CUG_Check

Callallowed?

Set result:Forward

Setforwardinginformation

Send InfoFor IncomingCall ack

Idle

Set negativeresponse:CUG reject


Idle

Yes

No

Figure 56f: Process ICH_VLR (sheet 6)


Procedure in the VLR to derive the requested basic service for an incoming (MT) call

Procedure Derive_Requested_Basic_Service_VLR DRBS_V1(1)

Basic service included inSend Info For Incoming Call?

Basic service:=BS received in

SIFIC

GSM BC received inProvide Roaming Number

Basic service:=BS derived from

GSM BC

Basic service:=default

Yes

No

Yes

No

Figure 57: Procedure Derive_Requested_Basic_Service_VLR


Procedure in the VLRto search for an MS (i.e. page in all location areas)

Procedure Search_For_MS_VLR SRCH_V1(1)


Search For MS

Page type=Circuit-switched call

Wait_For_Search_Result

Abort

Result:=Aborted

SearchFor MS negativeresponse

Result:=Fail

SearchFor MS ack

UpdateLocationArea ID

Result:=Pass

Figure 58: Procedure Search_For_MS_VLR


Procedure in the VLR to retrieve subscription information for the Call Waiting service

Procedure Get_CW_Subscription_Info_VLR CWI_VLR1(1)


handlingof CW

Wait_For_CW_Info

Abortprocesscallwaiting

From MSC

Figure 59: Procedure Get_CW_Subscription_Info_VLR


Procedure in the VLRto retrieve subscription information for the CLIP & COLR line identificationservices for an MT call

Procedure Get_LI_Subscription_Info_MT_VLR GLI_MTV1(1)

Initiatehandling of CLIP

Wait_For_CLIP_Info


Initiatehandling of COLR

Wait_For_COLR_Info


From process COLR_MAF040

To process COLR_MAF040

From process CLIP_MAF001

To process CLIP_MAF001

From MSC

From MSC

Figure 60: Procedure Get_LI_Subscription_Info_MT_VLR


Procedure in the VLRto handle Call Forwardingon Busy

Procedure Handle_CFB H_CFB1(1)


handlingof CFB

Wait_For_CFB_Result


Error?

Normalcall

busy?

Result:=Continue

Result:=Forward

Result:=Fail

No

Yes

No

Yes

Figure 61: Procedure Handle_CFB


Procedure in the VLRto handle Call Forwardingon No subscriber Reply

Procedure Handle_CFNRy H_CFNRy1(1)


handlingof CFNRy

Wait_For_CFNRy_Result


Error?

Normalcall?

Result:=Continue

Result:=Forward

Result:=Fail

No

Yes

No

Yes

Figure 62: Procedure Handle_CFNRy


8 Contents of messages

This clause specifies the content of each message shown in clauses 5 & 7, except for the followingmessages, which are not specific to call handling:

On the D interface (VLR-HLR):- Abort;- Activate Trace Mode- Insert Subscriber Data- Send Authentication Info;- Send Authentication Info ack;- Send Authentication Info negative response;

In the tables which follow, information elements are shown as mandatory (M), conditional (C) or optional(O). A mandatory information element shall always be present. A conditional information element shall bepresent if certain conditions are fulfilled; if those conditions are not fulfilled it shall be absent. An optionalelement may be present or absent, at the discretion of the application at the sending entity.

8.1 Messages on the B interface (MSC-VLR)

8.1.1 Abort

The following information element is required:

Information element name Required DescriptionAbort reason M Indicates the reason for the procedure being aborted.

8.1.2 Authenticate

The following information elements are required:

Information element name Required DescriptionRAND M Random number challenge to be sent to the MS [3]CKSN M Cipher key sequence number to be sent to the MS [3]

8.1.3 Authenticate ack


Information element name Required DescriptionSRES M Signature result returned by the MS [3]

8.1.4 Check IMEI

This message contains no information elements.

8.1.5 Check IMEI ack


Information element name Required DescriptionEquipment status M Indicates whether the ME is black-listed, grey-listed or

white-listed

8.1.6 Check IMEI negative response

The negative response information element can take the following values:

- System failure;- Unknown equipment.


8.1.7 Complete Call



Information element name Required DescriptionMSISDN C MSISDN of the MS for which the Complete Call is sent.

Shall be present for an ordinary MO call, for an MT call andfor an emergency call when the MS is registered in theVLR; otherwise shall be absent.

IMEI C IMEI of the mobile for which the Complete Call is sent.Shall be present for an emergency call when the mobile isidentified only by its IMEI; otherwise shall be absent.

Category C Category of the MS for which the Complete Call is sent.Shall be present for an ordinary MO call and for anemergency call when the MS is registered in the VLR;otherwise shall be absent.

GSM bearer capability C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.

ISDN bearer capability C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.

ISDN low layer compatibility C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.

ISDN high layer compatibility C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.

CLIP provision C Indicates that CLIP is provisioned. Shall be present for anMT call if CLIP is provisioned; otherwise shall be absent.

CLIR override provision C Indicates that the CLIR override subscription option ofCLIP is provisioned. Shall be present for an MT call if CLIPis provisioned with the CLIR override subscription optionand the MS is registered in the HPLMN country; otherwiseshall be absent.

CLIR provision C Indicates that CLIR is provisioned. Shall be present for anMO call if CLIR is provisioned; otherwise shall be absent.

CLIR mode C Indicates the mode in which CLIR is provisioned:permanent, temporary (default presentation allowed) ortemporary (default presentation restricted). Shall bepresent for an MO call if CLIR is provisioned; otherwiseshall be absent.

COLP provision C Indicates that COLP is provisioned. Shall be present for anMO call if COLP is provisioned; otherwise shall be absent.

COLR override provision C Indicates that the COLR override subscription option ofCOLP is provisioned. Shall be present for an MO call ifCOLP is provisioned with the COLR override subscriptionoption and the MS is registered in the HPLMN country;otherwise shall be absent.

COLR provision C Indicates that COLR is provisioned. Shall be present for anMT call if COLR is provisioned; otherwise shall be absent.

No Reply Condition Timer C Value of timer to be used to determine the No subscriberreply condition. Shall be present for an MT call if the CallForwarding on No Reply service is active and operative;otherwise shall be absent.

CUG index C For the definition of this IE, see [11]. May be present (as anetwork operator option) for an ordinary MO call if the callis a CUG call; shall be present for an MT call if the call is aCUG call; otherwise shall be absent.

CUG interlock C For the definition of this IE, see [11]. Shall be present foran ordinary MO call if the call is a CUG call; otherwise shallbe absent.

CUG outgoing access C For the definition of this IE, see [11]. Shall be present foran ordinary MO call if the call is a CUG call with outgoingaccess; otherwise shall be absent.

Advice of Charge provision C Indicates whether Advice of Charge (Information) or Adviceof Charge (Charging) is provisioned. Shall be present foran ordinary MO call or an MT call if Advice of Charge isprovisioned; otherwise shall be absent.


8.1.8 Complete Call ack


8.1.9 Complete Call negative response


- Absent subsccriber;- Busy subscriber;- No subscriber reply;- Radio congestion.

8.1.10 Forward New TMSI


Information element name Required DescriptionTMSI M TMSI to be sent to the MS.

8.1.11 Forward New TMSI ack


8.1.12 Forward New TMSI negative response

The negative response information element can take the following value:

- TMSI reallocation failure.

8.1.13 Obtain Subscriber Info


Information element name Required DescriptionIMSI M IMSI of the MS for which information is required.Location informationrequested

C Indicates that the VLR requires location information for theMS. Shall be present if location information is required;otherwise shall be absent.

Subscriber state requested C Indicates that the VLR requires state information for theMS. Shall be present if state information is required;otherwise shall be absent.

8.1.14 Obtain Subscriber Info ack


Information element name Required DescriptionCell global identity C Identity of the cell from which the MS established a radio

transaction. Shall be present if the VLR requested locationinformation and the mobile is currently engaged on a radiotransaction; otherwise shall be absent.

Age of location information C Time in minutes since the MS last established a radiotransaction. Shall be present if the VLR requested locationinformation; otherwise shall be absent.

Subscriber state C Indicates whether the MS is busy (i.e. engaged on a circuit-switched call) or assumed idle. Shall be present if the VLRrequested state information; otherwise shall be absent.

8.1.15 Page MS



Information element name Required DescriptionIMSI M IMSI of the MS to be paged.Location area ID M Location area in which the MS is to be paged.Page type M Indicates whether the paging is for a circuit-switched call,

MT SMS delivery or SS activityTMSI O TMSI to be broadcast to identify the MS.

8.1.16 Page MS negative response


- Absent subscriber;- Busy subscriber (More calls possible);- Busy subscriber (NDUB);- System failure;- Unknown location area ID.

The Page MS negative response Busy subscriber (More calls possible) also indicates the basic servicewhich applies for the established call.

8.1.17 Process Access Request


Information element name Required DescriptionCM service type M Indicates the type of access required: normal MO call,

emergency call or page response. Other values (shortmessage service and SS request) defined for this IE arenot considered in this specification.

Access connection status M Indicates whether or not the connection to the MS isciphered and whether or not it is authenticated.

Current location area ID M Identity of the location area from which the access requestwas received.

IMSI C IMSI of the MS requesting the access. For normal MO callor page response, one of IMSI or TMSI shall be present.For emergency call, one of IMSI, TMSI or IMEI shall bepresent.

TMSI C TMSI of the MS requesting the access. For normal MO callor page response, one of IMSI or TMSI shall be present.For emergency call, one of IMSI, TMSI or IMEI shall bepresent.

IMEI C IMEI of the MS requesting the access. For normal MO callor page response, one of IMSI or TMSI shall be present.For emergency call, one of IMSI, TMSI or IMEI shall bepresent.

CKSN C Cipher key sequence number of the MS requesting theaccess. Shall be present if TMSI is present; otherwise shallbe absent.

8.1.18 Process Access Request ack


Information element name Required DescriptionIMSI C IMSI of the MS requesting the access. For normal MO call

or page response, shall be present. For emergency call,one of IMSI or IMEI shall be present.

IMEI C IMEI of the MS requesting the access. For normal MO callor page response, shall be absent. For emergency call,one of IMSI or IMEI shall be present.

MSISDN O MSISDN of the MS requesting the access.


8.1.19 Process Access Request negative response


- Roaming not allowed;- System failure;- Unidentified subscriber;- Illegal equipment;- Illegal subscriber.

8.1.20 Process Call Waiting


Information element name Required DescriptionMSISDN M MSISDN of the MS for which the Process Call Waiting is

sent.GSM bearer capability C Shall be present if it was received in the Provide Roaming

Number for the waiting call; otherwise shall be absent.ISDN bearer capability C Shall be present if it was received in the Provide Roaming

Number for the waiting call; otherwise shall be absent.ISDN low layer compatibility C Shall be present if it was received in the Provide Roaming

Number for the waiting call; otherwise shall be absent.ISDN high layer compatibility C Shall be present if it was received in the Provide Roaming

Number for the waiting call; otherwise shall be absent.CLIP provision C Indicates that CLIP is provisioned. Shall be present if CLIP

is provisioned; otherwise shall be absent.CLIR override provision C Indicates that the CLIR override subscription option of

CLIP is provisioned. Shall be present if CLIP is provisionedwith the CLIR override subscription option and the MS isregistered in the HPLMN country; otherwise shall beabsent.

COLR provision C Indicates that COLR is provisioned. Shall be present ifCOLR is provisioned; otherwise shall be absent.

No Reply Condition Timer C Value of timer to be used to determine the No subscriberreply condition. Shall be present if the Call Forwarding onNo Reply service is active and operative; otherwise shallbe absent.

CUG index C For the definition of this IE, see [11]. Shall be present if thewaiting call is a CUG call; otherwise shall be absent.

Advice of Charge provision C Indicates whether Advice of Charge (Information) or Adviceof Charge (Charging) is provisioned. Shall be present ifAdvice of Charge is provisioned; otherwise shall be absent.

8.1.21 Process Call Waiting ack


8.1.22 Process Call Waiting negative response


- Busy subscriber;- No subscriber reply.

8.1.23 Provide IMEI


8.1.24 Provide IMEI ack



Information element name Required DescriptionIMEI M IMEI of the ME involved in the access request.

8.1.25 Provide IMSI


8.1.26 Provide IMSI ack


Information element name Required DescriptionIMSI M IMSI of the MS involved in the access request.

8.1.27 Search For MS


Information element name Required DescriptionIMSI M IMSI of the MS to be paged in all location areas.Page type M Indicates whether the paging is for a circuit-switched call,

MT SMS delivery or SS activityTMSI O TMSI to be broadcast to identify the MS.

8.1.28 Search For MS ack


Information element name Required DescriptionLocation area ID M Location area in which the MS responded to the page.

8.1.29 Search For MS negative response


- Absent subscriber;- Busy subscriber (More calls possible);- Busy subscriber (NDUB);- System failure.

The Search For MS negative response Busy subscriber (More calls possible) also indicates the basicservice which applies for the established call.

8.1.30 Send Info For Incoming Call



Information element name Required DescriptionMSRN M Mobile Station Roaming Number received in the IAM.Bearer service C GSM bearer service required for the MT call. Shall be

present if the MSC was able to derive a GSM bearerservice from ISDN BC/LLC/HLC information received in theIAM; otherwise shall be absent.

Teleservice C GSM teleservice required for the MT call. Shall be presentif the MSC was able to derive a GSM teleservice fromISDN BC/LLC/HLC information received in the IAM;otherwise shall be absent.

Dialled number C Number dialled by the calling subscriber. Shall be presentif it was received in the IAM; otherwise shall be absent.

Number of forwarding C Number of times the incoming call has already beenforwarded. Shall be present if it was received in the IAM;otherwise shall be absent.

CUG interlock C For the definition of this IE, see [11]. Shall be present if itwas received in the IAM; otherwise shall be absent.

CUG outgoing access C For the definition of this IE, see [11]. Shall be present if itwas received in the IAM; otherwise shall be absent.

8.1.31 Send Info For Incoming Call ack


Information element name Required DescriptionIMSI M IMSI of the B subscriber.Forwarded-to number M E.164 number of the C subscriber.Forwarding reason M Indication of why the call has been forwarded (on mobile

subscriber busy, on mobile subscriber not reachable or onno subscriber reply).

Notification to calling party M Indication of whether the calling party is to be notified thatthe call has been forwarded.

Notification to forwardingparty

C Indication of whether the forwarding party is to be notifiedthat the call has been forwarded. Shall be present if the callis to be forwarded on mobile subscriber busy or on nosubscriber reply; otherwise shall be absent.

Forwarded-to subaddress C Subaddress of the C subscriber (see [2]). Shall be presentif a forwarded-to subaddress is stored in the VLR inassociation with the forwarded-to number; otherwise shallbe absent.

CUG interlock C For the definition of this IE, see [11]. Shall be present if theVLR has determined that the forwarded call is to be treatedas a CUG call in accordance with the rules in [11],otherwise shall be absent.

CUG outgoing access C For the definition of this IE, see [11]. Shall be present if theVLR has determined that the forwarded call is to be treatedas a CUG call with outgoing access in accordance with therules in [11], otherwise shall be absent.

8.1.32 Send Info For Incoming Call negative response


- Absent subscriber;- Busy subscriber;- CUG reject (Called party SS interaction violation);- Forwarding violation;- Impossible call completion;- No subscriber reply;- System failure;- Unallocated roaming number;


8.1.33 Send Info For Outgoing Call


Information element name Required DescriptionCalled number M E.164 number of the call destination.Bearer service C Bearer service required for the MO call, derived from the

GSM bearer capability information received in the setuprequest from the MS. One of bearer service or teleserviceshall be present.

Teleservice C Teleservice required for the MO call, derived from the GSMbearer capability information received in the setup requestfrom the MS or from the emergency setup request from theMS. One of bearer service or teleservice shall be present.

CUG index C For the definition of this IE, see [11]. Shall be present if itwas received in the setup request from the MS.

Suppress preferential CUG C For the definition of this IE, see [11]. Shall be present if itwas received in the setup request from the MS.

Suppress CUG outgoingaccess

C For the definition of this IE, see [11]. Shall be present if itwas received in the setup request from the MS.

8.1.34 Send Info For Outgoing Call negative response


- Bearer service not provisioned;- Call barred (Operator determined barring);- Call barred (Supplementary service barring);- CUG reject (Inconsistent access information - index incompatible with basic service);- CUG reject (Inconsistent access information - no CUG selected);- CUG reject (Outgoing calls barred within the CUG);- CUG reject (Unknown CUG index);- Teleservice not provisioned.

8.1.35 Set ciphering mode


Information element name Required DescriptionCiphering mode M Indicates whether ciphering of the radio connection is

required, and if so which ciphering algorithm is to be used.Kc C Ciphering key to be used if ciphering of the radio

connection is required. Shall be present if the cipheringmode indicates that ciphering of the radio connection isrequired, otherwise shall be absent.

8.1.36 Trace subscriber activity


Information element name Required DescriptionTrace reference M Reference number to be included with tracing reports

which the MSC sends to the OMCTrace type M For the definition of this IE, see [20]

8.1.37 Use existing TMSI



8.2 Messages on the C interface (MSC-HLR)

8.2.1 Send Routeing Info


Information element name Required DescriptionMSISDN M MSISDN of the B subscriber (see [2]).CUG interlock C For the definition of this IE, see [11]. Shall be present if the

GMSC received it in the IAM, otherwise shall be absent.CUG outgoing access C For the definition of this IE, see [11]. Shall be present if the

GMSC received it in the IAM, otherwise shall be absent.Number of forwarding C Number of times the incoming call has already been

forwarded. Shall be present if it was received in the IAM;otherwise shall be absent.

ISDN BC C ISDN bearer capability. Shall be present if the GMSCreceived it in the IAM, otherwise shall be absent.

ISDN LLC C ISDN lower layer compatibility. Shall be present if theGMSC received it in the IAM, otherwise shall be absent.

ISDN HLC C ISDN higher layer compatibility. Shall be present if theGMSC received it in the IAM, otherwise shall be absent.

8.2.2 Send Routeing Info ack


Information element name Required DescriptionIMSI M IMSI of the B subscriber (see [2]).Roaming number C E.164 number required to route the call to VMSCB (see

[2]). Shall be present if the HLR received it in the ProvideRoaming Number ack, otherwise shall be absent.

Forwarded-to number C E.164 number of the C subscriber. Shall be present if theHLR has determined that the call is to be forwarded,otherwise shall be absent.

Forwarded-to subaddress C Subaddress of the C subscriber (see [2]). Shall be presentif the HLR has determined that the call is to be forwardedand a forwarded-to subaddress is stored in the HLR inassociation with the forwarded-to number, otherwise shallbe absent.

Notification to calling party C Indication of whether the calling party is to be notified thatthe call has been forwarded. Shall be present if the HLRhas determined that the call is to be forwarded, otherwiseshall be absent.

Forwarding reason C Indication of why the call has been forwarded(unconditionally or on mobile subscriber not reachable).Shall be present if the HLR has determined that the call isto be forwarded, otherwise shall be absent.

CUG interlock C For the definition of this IE, see [11]. Shall be present if theHLR has determined that the call is to be treated as a CUGcall in accordance with the rules in [11], otherwise shall beabsent.

CUG outgoing access C For the definition of this IE, see [11]. Shall be present if theHLR has determined that the call is to be treated as a CUGcall with outgoing access in accordance with the rules in[11], otherwise shall be absent.

8.2.3 Send Routeing Info negative response


- Absent subscriber;- Bearer service not provisioned;- Call barred (Operator determined barring);


- Call barred (Supplementary service barring);- CUG reject (Called party SS interaction violation);- CUG reject (Incoming calls barred within CUG);- CUG reject (Requested basic service violates CUG constraints);- CUG reject (Subscriber not member of CUG);- Data missing;- Facility not supported;- Forwarding violation- Number changed;- System Failure;- Teleservice not provisioned;- Unexpected data value;- Unknown subscriber.

8.3 Messages on the D interface (VLR-HLR)

8.3.1 Provide Roaming Number


Information element name Required DescriptionIMSI M IMSI of the B subscriber (see [2]).MSC number M E.164 number which identifies VMSCB (see [2]).MSISDN O E.164 number which identifies the B subscriber. May be

present if the HLR requires it to be included in the call datarecord.

LMSI C Local Mobile Subscriber Identity. Shall be present if theLMSI was sent to HLRB at location updating.

GSM bearer capability C Information to define the GSM bearer capability requiredfor the call. For alternate speech/fax, alternate speech/dataor speech followed by data calls this information elementshall contain two GSM bearer capabilities, as specified inGSM 04.08. May be present if the HLR can determine therequired GSM bearer capability from ISDN compatibilityinformation received in the Send Routeing Info message,or from the MSISDN if a multi-numbering scheme is used;otherwise shall be absent. If the ISDN BC and ISDN LLCIEs are present, the GSM bearer capability IE shall beabsent.

ISDN BC C ISDN bearer capability. May be present if the HLR receivedit in the Send Routeing Info message, otherwise shall beabsent. If the GSM bearer capability IE is present, theISDN BC IE shall be absent.

ISDN LLC C ISDN lower layer compatibility. May be present if the HLRreceived it in the Send Routeing Info message, otherwiseshall be absent. If the GSM bearer capability IE is present,the ISDN LLC IE shall be absent.

ISDN HLC C ISDN higher layer compatibility. Shall be present if the HLRreceived it in the Send Routeing Info message, otherwiseshall be absent.

8.3.2 Provide Roaming Number ack


Information element name Required DescriptionRoaming number M E.164 number required to route the call to VMSCB (see

[2]).

8.3.3 Provide Roaming Number negative response



- Absent subscriber;- Data missing;- Facility not supported;- No roaming number available;- OR not allowed;- Unexpected data value.

8.3.4 Provide Subscriber Info


Information element name Required DescriptionIMSI M IMSI of the subscriber for whom information is requested

(see [2]).LMSI C Local Mobile Subscriber Identity. Shall be present if the

LMSI was sent to the HLR at location updating.Requested information M Indicates whether the HLR requires location information,

subscriber state or both location information andsubscriber state.

8.3.5 Provide Subscriber Info ack


Information element name Required DescriptionLocation information C Information to define the location of the MS: see definition

in subclause 8.3.5.1. Shall be present if locationinformation was requested and is available; otherwise shallbe absent.

Subscriber state C Indicates whether the MS is busy (i.e. engaged on a circuit-switched call), network determined not reachable (IMSIdetached or roaming in a prohibited location area) orassumed idle. Shall be present if subscriber state wasrequested; otherwise shall be absent.

8.3.5.1 Location information

The compound information element Location information consists of the following subordinate informationelements:

Information element name Required DescriptionLocation number C For a definition of this information element, see [21]. Shall

be present if the VLR can derive it from the stored cellglobal identity or location area identity; otherwise shall beabsent.

Cell ID C Cell global identity of the cell in which the MS lastestablished a radio transaction. Shall be present if theMSC/VLR can supply it; otherwise shall be absent. Shall beabsent if Location area ID is present.

Location area ID C Identity of the location area in which the MS lastestablished a radio transaction. Shall be present if theMSC/VLR can supply it; otherwise shall be absent. Shall beabsent if Cell ID is present.

Geographical information C For a definition of this information element, see [4]. Shallbe present if the VLR can derive it from the stored cellglobal identity or location area identity; otherwise shall beabsent.

VLR number M E.164 number which identifies the VLR (see [2]).Age of location information M Measured in minutes.


8.3.6 Provide Subscriber Info negative response


- Unexpected data value.

8.3.7 Restore Data


Information element name Required DescriptionIMSI M IMSI of the subscriber for whom data are to be restored

(see [2]).LMSI O LMSI of the subscriber for whom data are to be restored

(see [2]). May be included if required by the requestingVLR.

8.3.8 Restore Data ack


Information element name Required DescriptionHLR number M E.164 number which identifies the HLR (see [2]).MS not reachable flag C Indicates whether the VLR should notify the HLR when the

MS next establishes radio contact. Shall be present if thecorresponding indicator is set in the HLR record for thesubscriber; otherwise shall be absent.

8.3.9 Restore Data negative response


- System failure;- Unknown subscriber.

8.3.10 Provide Subscriber Info negative response


- Data missing;- Unexpected data value.

8.4 Messages on the F interface (MSC-EIR)

8.4.1 Check IMEI


Information element name Required DescriptionIMEI M IMEI of the ME whose status is to be checked (see [2]).

8.4.2 Check IMEI ack


Information element name Required DescriptionEquipment status M Indicates whether the ME is black-listed, grey-listed or

white-listed

8.4.3 Check IMEI negative response

The negative response information element can take the following value:


- Unknown equipment.


Annex A (Informative) Handling of an IAM at an MSC

An MSC which receives an IAM from an originating exchange may react in three different ways:

- It acts as a transit exchange, i.e. it relays the IAM to a destination exchange determined by analysisof the called party address, and thereafter relays other telephony signalling between the originatingand destination exchange until the connection is released. This behaviour is not specific to GSM;

- It acts as a terminating exchange, i.e. it attempts to connect the call to an MS currently registered inthe service area of the MSC;

- It acts as a GMSC, i.e. it interrogates an HLR for information to route the call. If the HLR returnsrouteing information, the MSC uses the routeing information from the HLR to construct an IAM,which it sends to a destination exchange determined by analysis of the routeing information fromthe HLR.

Sheet 1: when the MSC coordinating process has decided whether the MSC is to act as a terminatingVMSC, a GMSC or a transit exchange, it forwards the IAM to an idle instance of the appropriate process.

Sheet 2: after the MSC coordinating process has sent an IAM to an instance of the process MT_GMSC orICH_MSC, it acts as a transparent relay for messages received from the originating exchange and theprocess instance (denoted by ‘offspring’). After the MSC coordinating process has relayed a Releasemessage, it returns to the idle state.

Sheet 2: after the MSC coordinating process has sent an IAM to a destination exchange, it acts as atransparent relay for messages received from the originating exchange and the destination exchange.After the MSC coordinating process has relayed a Release message, it returns to the idle state.


Process in the MSC tohandle an incoming IAMand trigger the correct application process

Process MSC_Coord Coord_M1(2)

IDLE

InitialAddress

From originatingexchange

Called party address in MSRN rangefor this MSC?

HLR addressderivable?

InitialAddress

To processMT_GMSC

Relay_Information_

Internally

InitialAddress

To destinationdetermined byrouteing tables

Relay_Information_

Externally

InitialAddress

To processICH_MSC

No

Yes

No

Yes

Figure 63a: Process MSC_Coord (sheet 1)


Process in the MSC tohandle an incoming IAMand trigger the correct application process

Process MSC_Coord Coord_M2(2)

Relay_Information_

Internally

ReleaseFrom originatingexchange

Release To offspring

IDLE

Release From offspring

ReleaseTo originatingexchange

IDLE*From originatingexchange

- To offspring

Relay_Information_

Internally

* From offspring

-To originatingexchange

Relay_Information_

Internally

Relay_Information_

Externally

ReleaseFrom originatingexchange

ReleaseTodestinationexchange

IDLE

ReleaseFromdestinationexchange

ReleaseTo originatingexchange

IDLE*From originatingexchange

-Todestinationexchange

Relay_Information_

Externally

*From destinationexchange

-To originatingexchange

Relay_Information_

Externally

Figure 63b: Process MSC_Coord (sheet 2)


History

Document history

Date Status Comment

January 1997 Proposed version 2.1.0 Presented to SMG3, Dresden

Documents

Basic Call Handling GSM 03.18