V.2 UE Provided Access Information in Untrusted WLAN access

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

A UE accessing IMS via untrusted WLAN shall support the following:

– If available, provide the identity of the WLAN AP the UE is currently associated with, and used for IMS signalling at IMS registration, IMS emergency registration, IMS session initiation, SMS over IP, and in any procedure defined in TS 24.229 [10a], where access network information is provided.

– If available, provide geographical location coordinates during IMS emergency session setup.

– Provide the cell information (cell-ID) for the most recent seen cell at IMS registration, IMS emergency registration, IMS emergency session initiation, and in any procedure defined in TS 24.229 [10a] where access network information is provided. The cell-ID access information shall include additional information describing when the information about the cell-ID was collected and that can be used to calculate the "age" of the information. The information about the cell-ID shall be included in an appropriate field of the SIP request that is distinguished from the information about the access network currently used to transport SIP signalling (i.e. Untrusted WLAN).

NOTE: Operator specific local control policies may be applied and which can result in a registration being accepted, rejected, and/or may also result in additional implementation specific actions. Any node that participates in the registration process (e.g. P-CSCF, HSS) may apply these local control policies.

Annex W (normative):
Support of IMS Services for roaming users in deployments without IMS-level roaming interfaces