R.5 Session Establishment/Modification – Location Information Distributed by IMS AS

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

The call flow in this clause describes the procedures to distribute user location and/or UE Time Zone information provided by the network within IMS session establishment/modification signalling when the retrieval of user location and/or UE Time Zone information is performed by an IMS AS.

Figure R.5-1: User location and/or UE Time Zone information Distribution by an IMS AS

Terminating Side:

1. A SIP INVITE request is received bv an AS.

2. The INVITE is processed by the AS and returned to the S-CSCF.

NOTE 1: If the AS requires user location and/or UE Time Zone information for the service execution as such, the user location and/or UE Time Zone information can be fetched prior sending the INVITE to the next hop.

3. The SDP Answer is received by the AS.

4. The AS retrieves user location and/or UE Time Zone information from the access network via the HSS.

The HSS retrieves the requested information from the Access Network

The HSS/UDM may not be aware whether the UE is currently camping on 3GPP or Non 3GPP access and may need to request Location Information from the AMF, the MME, the SGSN and from the TWAN (via the AAA server in this last case).

The HSS provides the AS with the requested information. When the HSS has received multiple user location (from multiple access: 3GPP and non 3GPP), the HSS provides the AS with the most recent user location.

5. The AS includes the user location and/or UE Time Zone information obtained from the access network via the HSS and sends the SDP answer towards the S-CSCF.

NOTE 2: The S-CSCF may further distribute user location and/or UE Time Zone information to other ASs within the trust domain.

Originating Side:

6. A SIP INVITE request is received by an AS.

7. The AS retrieves user location and/or UE Time Zone information from the access network via the HSS. The same procedures as described in steps 4a and 4b above apply.

8. The AS includes the user location and/or UE Time Zone information obtained from the access network via the HSS and sends the INVITE towards the S-CSCF.

NOTE 3: The S-CSCF can further distribute user location and/or UE Time Zone information to other ASs within the trust domain. The S-CSCF does not distribute the user location and/or UE Time Zone information to the P-CSCF.