IP Multimedia Subsystem (IMS) emergency sessions
This document defines the stage 2 service description for emergency services in the IP Multimedia Core Network Subsystem (IMS), including the elements necessary to support IP Multimedia (IM) emergency services and IM emergency services for eCall. ITU‑T Recommendation I.130 [4] describes a three-stage method for characterisation of telecommunication services and ITU‑T Recommendation Q.65 [3] defines stage 2 of the method.
This document covers also the Access Network aspects that are crucial for the provisioning of IMS emergency services. Other 3GPP specifications that are related to the IMS emergency services are TS 23.228 [1] on IMS in general, including fixed broadband access aspects, TS 23.060 [2] describing GPRS (UTRAN): TS 23.401 [28] describing EPS (UTRAN and E-UTRAN); TS 23.402 [29] describing Non 3GPP access (WLAN) to EPC; TS 23.271 [5] that covers location services; TS 23.216 [31] and TS 23.237 [32] describing Single Radio Voice Call Continuity (SRVCC) and Dual Radio Voice Call Continuity (DRVCC) for IMS Emergency session, TS 23.292 [45] describing the use of IMS services when using CS access for the media bearer and TS 23.501 [48] and TS 23.502 [49] describing support of emergency services and location for 5GS. TS 25.301 [6] contains an overall description of the UMTS Terrestrial Radio Access Network; TS 36.300 [30] contains an overall description of the Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); and TS 38.300 [50] contains an overall description of the Next Generation Radio Access Network (NG-RAN). Other non-3GPP specifications that are related to the IMS emergency services include 3GPP2 cdma2000 HRPD IP‑CAN, as specified in 3GPP2 X.S0060 [25] when the UE is connected to a PDS core network and 3GPP2 X.S0057‑A [39] when the UE is connected to an EPC core network.
The emergency support in different IP-CANs is described in the Informative Annex E.