The IP Multimedia Subsystem (IMS) is a standardized architectural framework designed to deliver IP-based multimedia services. Developed by the 3rd Generation Partnership Project (3GPP), IMS enables telecom operators to provide a unified and flexible platform for voice, video, messaging, and data services across both fixed and mobile networks.

IMS is essential in converging voice and multimedia communications over an all-IP network, making it a key component of next-generation networks (NGNs), including LTE, 5G, and Wi-Fi calling.

What Is IP Multimedia Subsystem (IMS)?
At its core, IMS separates service delivery from the underlying transport network. It leverages standard internet protocols like Session Initiation Protocol (SIP) to initiate, manage, and terminate real-time communication sessions. IMS makes it possible for different devices and networks to seamlessly interoperate, enabling features like:

Voice over LTE (VoLTE)

Video calling

Rich Communication Services (RCS)

Push-to-talk over cellular (PoC)

Presence services

IP messaging and conferencing