Review of IP multimedia subsystem

Abstract

The IP Multimedia Subsystem (IMS) defines a network that has an all-IP core. This enables it to provide convergence across multimedia applications. Legacy networks like PSTN, PLMN are being rapidly phased out and an all-IP based flat network is close to realization. Nevertheless, legacy networks stil form an important part of Telecommunication domain. The IP Multimedia Subsystem supports such legacy networks and provides enhanced data and voice services based on an IP network. It has been conceived for telecom operators willing to provide advanced services on top of mobile and fixed networks. It aims to achieve the converged communications paradigm by merging the Internet and Telecommunication domains. IMS not only offers rich multimedia content along with voice and data services but also has provisions for service integration to provide a seamless and user-centric experience. Session Initiation Protocol (SIP) has been standardized as the signalling protocol tobe used in the IMS. SIP allows for ubiquitous access to many useful Internet services as well as several new and Innovative ones such as Presence, Push-to-Talk etc. This paper is a brief review of IMS and its core components. It also presents a high level overview of the IMS services and the security aspect in IMS.