Feature Description

Important

The PGW-C term used in this chapter denotes the EPS interworking functionality supported by SMF and must not be assumed as a standalone P-GW that is used in the LTE network.

The SMF supports Voice over Long-Term Evolution or LTE (VoLTE). The VoLTE technology utilizes IP Multimedia Subsystem (IMS) to allow you to make cellular calls over the LTE access network.

SMF supports prioritization of emergency and VoLTE calls during ICSR switchover and recovery. The SMF tracks IMS sessions with active voice calls and communicates with UPF. Then, UPF prioritizes the Emergency and VoLTE calls during ICSR switchover and recovery. SMF supports only the Wireless Priority Services (WPS) call prioritization where the MP flag is configured in N4 and the GTP headers are based on the WPS configuration.