5.16.3.2a IMS voice over PS Session Supported Indication over non-3GPP access

The serving PLMN AMF shall send an indication toward the UE during the Registration procedure over non-3GPP access to indicate whether an IMS voice over PS session is supported or not supported via non-3GPP access. A UE with "IMS voice over PS" voice capability over non-3GPP access should take this indication (received in the Registration procedure performed over either 3GPP access or Non-3GPP access) into account when performing the selection between N3IWF/TNGF and ePDG described in clause 6.3.6.

The serving PLMN AMF may only indicate IMS voice over PS session supported over non-3GPP access if the network is able to provide a successful IMS voice over PS session over N3IWF/TNGF connected to 5GC with a 5G QoS Flow that supports voice as specified in clause 5.7.