School of Specs 23.501v20.2.0

3GPP 23.501 v20.2.0 — the document's own text

5.16.3.1 General

Taught in 21. Emergency calls, messages, voice and location (The 5G system architecture, in depth).

IP-Connectivity Access Network specific concepts when using 5GS to access IMS can be found in TS 23.228 [15].

5GS supports IMS with the following functionality:

  • Indication toward the UE if IMS voice over PS session is supported.
  • Capability to transport the P-CSCF address(es) to UE.
  • Paging Policy Differentiation for IMS as defined in TS 23.228 [15].
  • IMS emergency service as defined in TS 23.167 [18].
  • Domain selection for UE originating sessions.
  • Terminating domain selection for IMS voice.
  • Support of P-CSCF restoration procedure (clause 5.16.3.9).
  • NRF based P-CSCF discovery (clause 5.16.3.11).

NOTE: The NRF based P-CSCF discovery has no impact on the UE, i.e. the UE does not need to know how P-CSCF IP address(es) is discovered in the network.

  • NRF based HSS discovery (clause 5.16.3.12).