IMS in 5G: architecture and role of each component

Why IMS Powers Voice in 5G

The IP Multimedia Subsystem (IMS) is the signaling framework that enables voice, video, and multimedia services over IP networks. In 5G, IMS is the mandatory voice solution — there is no circuit-switched fallback. The architecture consists of several specialized components: P-CSCF serves as the UE's first contact point discovered during IMS PDU session setup. I-CSCF is the entry point into the home network that queries UDM to locate the S-CSCF. S-CSCF acts as the central session controller and SIP registrar. TAS provides supplementary telephony services, and MGCF handles PSTN interworking.