IMS support for 5GC is defined in TS 23.228.
The 5G System architecture supports N5 interface between PCF and P-CSCF and supports Rx interface between PCF and P-CSCF, to enable IMS service. See TS 23.228, TS 23.503 and TS 23.203.
Location Service feature is optional and applicable to both regulatory services and commercial services in this Release of the specification. The non-roaming and roaming architecture to support Location Services are defined in clause 4.2 of TS 23.273.
See clause 126.96.36.199 of TS 23.502.
Application trigger message contains information that allows the network to route the message to the appropriate UE and the UE to route the message to the appropriate application. The information destined to the application, excluding the information to route it, is referred to as the Trigger payload. The Trigger payload is implementation specific.