The IP Multimedia Subsystem is a system for delivering IP Multimedia Services and is extremely important for IT service and software farms all over the world.

IP multimedia subsystems are employed in every IT industry around the world, including Germany, Mexico, and Japan. The IP multimedia subsystem is a unified architectural framework for providing IP audio-video applications via a network that functions similarly to a circuit switch. Handheld digital telephone services over an IP network have traditionally used a packet-switch-style network rather than an IP packet-switched network to handle voice calls. Compared to classic circuit-switch technologies, packet switching and the IP multimedia layer provide considerable advantages. More services may now be supplied via IP networks at higher speeds and at lower costs thanks to the IP multimedia subsystem. There are two primary benefits to using IP multimedia subsystem over traditional circuit-switch networks: better-integrated media access and greater portability. In regions such as Germany, the prevalence of IT companies has increased the requirement for IP multimedia subsystem. For instance, according to TeleTrusT, in 2018, there were around 92.7 thousand companies in the IT services and software segment in Germany.

Most modern IP multimedia subsystem uses high-speed circuit switches that incorporate circuit-switch functionality with a multimedia receiver. This means that when a user calls from a PC with an IP multimedia subsystem, the call goes through an IP multimedia subsystem first, before being routed over a conventional circuit network. Since the IP multimedia subsystem does not use packet switching, the PC can always be on even when it is not connected to any wireless carrier. This means that, as long as there is an active Internet connection, the user can make and receive phone calls on any IP Multimedia Subsystem without any degradation to the quality of the audio or video signal being transmitted.

Multiple routing protocols can be created by the IP multimedia subsystem, allowing the same IP multimedia subsystem to be utilised with different standard network designs. These router protocols specify the IP multimedia subsystem's basic format and requirements, as well as the system's functioning. Although routing protocols varies amongst IP multimedia subsystem adapters, they usually incorporate some of the functions listed below. The advantage of using an IP multimedia subsystem as compared with a separate device for this purpose is that, with an IP multimedia subsystem, any gateway the host uses will connect to the core network of the company rather than the specific adapter, which ensures that all signals will arrive and leave at the same time.