B.4.12 Incoming call to a roaming subscriber handled by CAMEL

12.053GPPSubscriber Related Call and Event DataTS

Figure B.12 illustrates an incoming call from a fixed network subscriber "A" to a mobile CAMEL subscriber "B" who is currently roaming in another PLMN.

The call is first routed to a GMSC (1) and the GMSC shall create an incoming gateway record for fixed network accounting purposes.

The GMSC interrogates the HLR of the called subscriber in order to fetch the T-CSI (2). The HLR shall create an HLR interrogation record.

The "B" subscriber has an active T-CSI. Therefore the GMSC requests instructions from the gsmSSF which passes the CAMEL service key to a gsmSCF to indicate which service logic it should apply (3).

The gsmSCF may interrogate the HLR for subscriber information. As a network option, the operator may refuse to provide the requested information.

When gsmSCF processing is complete the call control is returned to the GMSC. The GMSC shall generate a terminating CAMEL interrogation record which contains T-CSI data.

The GMSC interrogates the HLR in order to determine his current location (4). The HLR shall create an HLR interrogation record.

The GMSC routes the call to the VPLMN in which subscriber "B" is currently located (5). The GMSC shall create an outgoing gateway record for accounting purposes. The GMSC shall also create a roaming record. This record includes the IMSI of the "B" subscriber and may be used as a cross-check for the TAP information received from the VPLMN.

The call is then routed by the VPLMN to the MSC at which the subscriber is currently located (6). The GMSC of the VPLMN shall produce an incoming gateway record and the terminating MSC shall create an MTC record for the call to "B".

The records generated are subsequently transferred to the OS of the appropriate PLMN (A). The MTC record generated by the terminating MSC shall be employed to create the appropriate MTC TAP record. The TAP records shall be included in a TAP file and transmitted to the HPLMN (B).

The following records are generated in HPLMN in this call scenario:

GMSC

MSC

HLR

Incoming gateway record

HLR interrogation record

Terminating CAMEL int. record

Roaming record

Outgoing gateway record

The following records are generated in VPLMN in this call scenario:

GMSC

MSC

HLR

Incoming gateway record

MTC record

Figure B.12: Incoming call to a roaming subscriber handled by CAMEL