E.7 Retrieval of Network Provided Location Information in GPRS/EPS

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

Information related to the location of the user provided by the access network may be required in IMS in order to comply with regulatory requirements (e.g. data retention, lawful interception) and/or in order to enable certain types of added value services based on the user’s location.

Depending on usage scenario, the following mechanisms are defined and can be used to retrieve the user location and/or UE Time Zone information from the access network when using GPRS and/or EPS to access IMS:

– The P‑CSCF can retrieve the user location and/or UE Time Zone information using PCC mechanisms as specified in TS 23.203 [54] and in TS 29.214 [11]. Operator policy determines whether to provide the user location and/or UE Time Zone information from the access network in the INVITE request, a MESSAGE request, or within a subsequent message of the dialog.

– When the user location and/or UE Time Zone information is required from the access network but not already available (e.g. when required in an INVITE request, when it is needed prior to session delivery, or when call is broken out to a MGCF), an IMS AS can trigger the retrieval of the user location and/or UE Time Zone information from the SGSN/MME via the HSS as specified in TS 29.328 [79] and as described in clause 4.2.4a.

Operator policies at P-CSCF and IMS AS need to be coordinated in order to ensure that the appropriate method to retrieve the user location and/or UE Time Zone information is used for specific scenarios according to operator’s preferences. The IMS entity that retrieves the user location and/or UE Time Zone information shall have the capability to further distribute the information to other IMS entities once it has been retrieved. User location and/or UE Time Zone information provided in the signalling by the network shall be possible to distinguish from user location information provided by the UE. The transfer of the user location and/or UE Time Zone information within IMS signalling shall not affect the transfer of any UE provided user location information. Information flows on how user location and/or UE Time Zone information can be further distributed within IMS depending on the alternative mechanism used can be found in Annex R.

The level of granularity of user location information may be changed at network/trust boundaries. Thus, the level of user location information granularity that can be retrieved by an IMS AS via the HSS-based procedures in roaming scenarios depends on inter-operator agreement, and needs to be aligned with policies in the P-CSCF.

Information related to the location of the user provided by the access network may be required in IMS in order to comply with regulatory requirements for SMS over IP. The P-CSCF applies the above mechanisms upon reception of a MESSAGE including the distribution of received information to other IMS entities.