11.6 Functional requirement of GCR

03.683GPPStage 2TSVoice Group Call Service (VGCS)

The process in the GCR is shown in figure 11.

Service subscriber initiated call

If the GCR receives an interrogation request for a call initiated by a service subscriber who is located in the MSC area of the associated MSC, the GCR calculates the group call reference from the Group ID and the originating cell ID.

If the group call reference was successfully calculated, the GCR checks whether a VGCS call with that group call reference is already on-going.

If the call is not marked as on-going, the GCR checks whether an anchor MSC address is stored in its group call reference record. If this is the case, a positive response including the anchor MSC address is returned to the MSC, the IMSI of the initiating service subscriber is stored in the GCR and the process returns to the idle state. If no anchor MSC address is stored (i.e. the associated MSC is anchor MSC with respect to this group call reference) the GCR marks its group call reference record with "on-going call" and returns a positive response including the group call attributes to the MSC and the process returns to the idle state.

If the group call reference could not be successfully calculated from the Group ID and the originating cell ID, the GCR returns a negative response indicating "failure" to the MSC and the process returns to the idle state.

If the call was marked as on-going, the GCR returns a negative response indicating "on-going call" to the MSC and the process returns to the idle state.

Dispatcher initiated call

If the GCR receives an interrogation request for a call initiated by a dispatcher or by a service subscriber who is not located in the MSC area of the associated MSC, the GCR checks the CLI of the initiator against the list of identities of dispatchers which are allowed to initiate the voice group call and against the VGCS prefix plus group call reference in order to determine whether the initiator is allowed to set-up the call. If the check is successful the GCR checks whether a VGCS call with the same group call reference is already on-going.

If the call is not marked as on-going, the GCR marks its group call reference record with "on-going call" and returns a positive response including the group call attributes to the MSC and the process returns to the idle state.

If the CLI check was not successful, the GCR returns a negative response indicating "failure" to the MSC and the process returns to the idle state.

If the call was marked as on-going, the GCR returns a negative response indicating "on-going call" to the MSC and the process returns to the idle state.

Anchor MSC triggered call

If the GCR (associated to a relay MSC) receives an interrogation request for a call triggered by the anchor MSC, the GCR deletes the IMSI of the initiating service subscriber which is possibly stored in its record, marks its group call reference record with "on-going call", returns a positive response including the list of cells inside the MSC area of the requesting MSC in which the call is to be sent to the MSC and the process returns to the idle state.

Call release

If the GCR receives a call released indication from the MSC, the "on-going call" indicator in the group call reference record is reset and the process returns to the idle state.

Figure 11: The process in the GCR (sheet 1 of 2)

Figure 11: The process in the GCR (sheet 2 of 2)