Service control architecture in the UMTS IP multimedia core network subsystem

The 3rd Generation Partnership Project (3GPP) UMTS networks promise to deliver an abundance of advanced, innovative, and feature-rich applications to end-users in a 3rd generation (3G) wireless environment. A core network IP multimedia subsystem (IMS) is being introduced as part of the 3G wireless environment. It aims to enable the convergence of, and access to, voice, video, messaging, data and Web-based technologies for the wireless user. The goal is to combine the growth of the Internet with the growth in mobile communications. The service control architecture for the IMS can be summarised as consisting of an application server, providing the execution environment for the applications, and communicating with the call state control function that handles the session control and mobility management functionality. Three general sets of standardised platforms for service control are being introduced in the UMTS IMS, each one addressing particular needs, from legacy service support to light weight SIP based support. The paper aims to provide an overview of the IMS service control architecture focusing on the rationale of the decisions taken in 3GPP.