7.8 Loss of Gm capability

23.2923GPPIP Multimedia Subsystem (IMS) centralized servicesRelease 17Stage 2TS

The Figure 7.8-1 provides an example flow for transfer of Service Control Signalling Path from Gm to I1 when the UE discovers Gm is not available and UE supports I1.

Figure 7.8-1: Service Control Signalling Path handover from Gm to I1

1. Upon detecting that there is a loss of Gm reference point, the ICS UE prepares to trigger the service control signalling path transfer.

2. ICS UE sends the service control signalling path transfer notification to the SCC AS over I1 requesting a switch to I1 for Service Control Signalling Path.

3. SCC AS accepts the transfer request, and returns the acknowledgement to ICS UE over I1.

After the above steps, the Service Control Signalling Path is switched from the Gm reference point to the I1 reference point.