Feasibility study on extension of support for IP Multimedia Subsystem (IMS) emergency calls
The present document provides a study investigating possible limitations of the solution for IMS emergency calls defined for Rel-7 in TS 23.167 [2], as well as possible extensions of that solution to reduce or eliminate some or all of the identified limitations.
The study item is expected mainly to concern IMS although some aspects of IP-CAN support may also be included. The study item has the following objectives
- Evaluate the feasibility of supporting IMS emergency calls for combinations of IP access network A and IMS core network B not supported in Rel-7 including but not limited to the following cases:
- A is any IP access network and B is the home 3GPP compliant IMS network for any emergency calling UE with adequate security credentials
- A is any IP access network and B is a visited 3GPP compliant IMS network for any emergency calling roaming UE with adequate security credentials
Additional user cases may also be proposed and evaluated during the SI if deemed applicable.
- Evaluate other enhancements to the solution for IMS emergency calls in Release 7 that may improve performance and/or reduce complexity
- Evaluate the feasibility of better aligning the solution in TS 23.167 [2] with applicable IETF standards and draft standards (e.g. from the Ecrit and Geopriv working groups)
- Any enhancement to the support of IMS emergency calls shall remain backward compatible to the solution in Rel-7 from the perspective of the UE and any 3GPP network element. Furthermore, any enhancement should be based on the solution in Rel-7 and should avoid unnecessarily adding new network entities, protocols and interfaces and moving existing functions from one entity to another.
The study item is expected to enable SA WG2 to decide which of the above objectives if any may be worth supporting in Rel-8 and which extensions to the current solution would then be appropriate.