IP Multimedia Subsystem (IMS)
The IP Multimedia Subsystem is the 3GPP-standardised architecture for delivering voice, video and messaging services over IP networks.
What is IP Multimedia Subsystem (IMS)?
IMS uses the SIP protocol to set up sessions. It is the platform behind VoLTE, Wi-Fi calling and 5G voice, and is used by fixed operators for digital voice services replacing the PSTN.