4.5.5 Handling of forwarded calls

23.0783GPPCustomised Applications for Mobile network Enhanced Logic (CAMEL) Phase 4Release 17Stage 2TS

The handling of forwarded calls in the GMSC or the terminating VMSC is specified in 3GPP TS 23.018 [12]. The processes and procedures specific to CAMEL are specified in this subclause.

– Procedure CAMEL_Check_ORLCF_VMSC;

– Procedure CAMEL_CF_MSC_INIT;

– Procedure CAMEL_CF_MSC_ALERTING;

– Procedure CAMEL_CF_MSC_ANSWER;

– Procedure CAMEL_CF_ETC;

– Procedure CAMEL_CF_CTR;

– Procedure CAMEL_MT_CF_LEG1_MSC;

– Process CAMEL_MT_CF_LEG2_MSC;

– Procedure CAMEL_MF_RECONNECT_MSC.

The procedure CAMEL_MT_CF_LEG1_MSC supervises the originating party only. The process CAMEL_MT_CF_LEG2_MSC supervises the forwarding-to party only. Hence, signals from the originating exchange are received by the procedure CAMEL_MT_CF_LEG1_MSC and signals from the destination exchange are received by the process CAMEL_MT_CF_LEG2_MSC.

A mobile terminated call can be forwarded either in the GMSC (indicated by provision of Forwarded-To-Number from the HLR or gsmSCF) or in the MSC (indicated by provision of Forwarded-To-Number from the VLR).

4.5.5.1 Procedure CAMEL_CF_MSC_INIT: handling of Int_Continue_With_Argument

The received parameters are used to overwrite the corresponding ISUP parameters (for mapping see 3GPP TS 29.078 [36]). Call parameters which are not included in the Int_Continue_With_Argument signal are unchanged.

Signalling limitations or regulatory requirements may require the Calling Partys Category, Generic Number, Original Called Party Number and Redirecting Party ID to be ignored or modified.

4.5.5.2 Procedure CAMEL_CF_MSC_INIT: handling of Int_Connect

The received parameters are used to overwrite the corresponding ISUP parameters (for mapping see 3GPP TS 29.078 [36]. Call parameters which are not included in the Int_Connect signal are unchanged.

As a network operator option, loop prevention mechanisms may cause the redirection information to be ignored or modified (e.g., if the Redirection counter has been decreased).

Signalling limitations or regulatory requirements may require the Calling Partys Category, Generic Number, Original Called Party Number and Redirecting Party ID to be ignored or modified.

The network signalling system shall indicate that this is an internal network number.

4.5.5.3 Procedure CAMEL_CF_MSC_INIT: handling of Int_Disconnect_Leg (Leg 2)

If the MSC receives Int_Disconnect_Leg (Leg 2) signal from the gsmSSF, in response to an Initial DP information flow, the MSC will continue the handling of the calling party (Leg1) without routeing the call to a destination.

4.5.5.4 Action of the MSC in procedure CAMEL_CF_MSC_ANSWER

If the MSC received a destination address from the GMSC in the ISUP Answer or ISUP Connect Message then the MSC relays the destination address to the gsmSSF in the Int_DP_O_Answer signal.

4.5.5.5 Action of the MSC in procedure CAMEL_CF_ETC

In procedure CAMEL_CF_ETC (sheet 2) the GMSC or terminating VMSC will remain in the Wait_For_Assisting_Answer state until it receives an ISUP Answer Message (ANM) or timeout occurs. This is to ensure that a call record is always generated for every successful establishment of a temporary connection to a gsmSRF, especially in the case where the connection is between PLMNs.

NOTE: This means that it may not be possible to access an SRF which does not generate an ISUP Answer Message (ANM).

Figure 4.77-1: Procedure CAMEL_Check_ORLCF_VMSC (sheet 1)

Figure 4.77-2: Procedure CAMEL_Check_ORLCF_VMSC (sheet 2)

Figure 4.78-1: Procedure CAMEL_CF_Dialled_Services (sheet 1)

Figure 4.79-1: Procedure CAMEL_CF_MSC_INIT (sheet 1)

Figure 4.79-2: Procedure CAMEL_CF_MSC_INIT (sheet 2)

Figure 4.79-3: Procedure CAMEL_CF_MSC_INIT (sheet 3)

Figure 4.79-4: Procedure CAMEL_CF_MSC_INIT (sheet 4)

Figure 4.80-1: Procedure CAMEL_SDS_CF_INIT (sheet 1)

Figure 4.80-2: Procedure CAMEL_SDS_CF_INIT (sheet 2)

Figure 4.80-3: Procedure CAMEL_SDS_CF_INIT (sheet 3)

Figure 4.80-4: Procedure CAMEL_SDS_CF_INIT (sheet 4)

Figure 4.81-1: Procedure CAMEL_NDS_CF_INIT (sheet 1)

Figure 4.81-2: Procedure CAMEL_NDS_CF_INIT (sheet 2)

Figure 4.81-3: Procedure CAMEL_NDS_CF_INIT (sheet 3)

Figure 4.81-4: Procedure CAMEL_NDS_CF_INIT (sheet 4)

Figure 4.82-1: Procedure CAMEL_CF_MSC_ALERTING (sheet 1)

Figure 4.82-2: Procedure CAMEL_CF_MSC_ALERTING (sheet 2)

Figure 4.82-3: Procedure CAMEL_CF_MSC_ALERTING (sheet 3)

Figure 4.83-1: Procedure CAMEL_CF_MSC_ANSWER (sheet 1)

Figure 4.83-2: Procedure CAMEL_CF_MSC_ANSWER (sheet 2)

Figure 4.83-3: Procedure CAMEL_CF_MSC_ANSWER (sheet 3)

Figure 4.84-1: Procedure CAMEL_CF_ETC (sheet 1)

Figure 4.84-2: Procedure CAMEL_CF_ETC (sheet 2)

Figure 4.84-3: Procedure CAMEL_CF_ETC (sheet 3)

Figure 4.84-4: Procedure CAMEL_CF_ETC (sheet 4)

Figure 4.85-1: Procedure CAMEL_CF_CTR (sheet 1)

Figure 4.85-2: Procedure CAMEL_CF_CTR (sheet 2)

Figure 4.85-3: Procedure CAMEL_CF_CTR (sheet 3)

Figure 4.85-4: Procedure CAMEL_CF_CTR (sheet 4)

Figure 4.85-5: Procedure CAMEL_CF_CTR (sheet 5)

Figure 4.86-1: Procedure CAMEL_MT_CF_LEG1_MSC (sheet 1)

Figure 4.86-2: Procedure CAMEL_MT_CF_LEG1_MSC (sheet 2)

Figure 4.86-3: Procedure CAMEL_MT_CF_LEG1_MSC (sheet 3)

Figure 4.86-4: Procedure CAMEL_MT_CF_LEG1_MSC (sheet 4)

Figure 4.86-5: Procedure CAMEL_MT_CF_LEG1_MSC (sheet 5)