R.4 Session Establishment/Modification at Mobile Termination

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

This information flow shows the procedure when operator policy requires the user location and/or UE Time Zone information from the access network to be included within IMS session establishment/modification signalling before sending the response towards the originating side.

Figure R.4-1: Mobile termination

1. The CSCF receives an incoming INVITE.

2. The CSCF send the INVITE to the P-CSCF.

3. The P-CSCF sends the INVITE to the UE.

4. The UE sends a response to the INVITE (the response can be either a provisional or final response). This can contain user location information provided by the UE.

5. The P-CSCF invokes procedures to obtain user location and/or UE Time Zone information from the access network. This step will be executed together with Authorization of QoS resources. In some scenarios, it might be possible to obtain or at least initiate the fetching of user location and/or UE Time Zone information already at step 3.

6. The P-CSCF adds the user location and/or UE Time Zone information obtained from the access network and sends the response towards the next CSCF, together with the user location information provided by the UE (if available).

7-9. The response is routed towards the originating party. The user location and/or UE Time Zone information may be removed or modified (e.g. to change location granularity to just indicate the serving PLMN) before routing outside the trust domain.