ABSTRACT
The Internet Protocol Multimedia Subsystem (IMS) was defined by the Third Generation Partnership Program (3GPP/3GPP2) as a generic standard architecture for offering IP multimedia services and also voice over IP. IMS was created initially as a standard for wireless networks. However, the wireline community, in the search for a unifying standard, has since realized the potential of IMS for fixed communication as well. Hence, it is being adopted for that purpose. As an international standard, it provides the framework and the support for fixed-to-mobile convergence [1] and hence the migration of all traffic from a circuit-switched domain to IP packetswitched domain in an all-IP network. The IMS inherently has the glue for working with the SIP for signaling and setting up IP sessions. As a 3GPP and subsequently international standard, it supports multiple access types, including GSM/GPRS, UMTS, CDMA2000, and HSDPA, broadband wireline access, and WLAN.
