Seamless mobility across IMS and legacy circuit networks

The growing desire of network providers to introduce support for voice over IP (VoIP) has created interesting challenges in the area of interoperability with existing wireless circuit networks. The 3rd Generation Partnership Project (3GPP) and the 3rd Generation Partnership Project 2 (3GPP2) standards have defined the IP Multimedia Subsystem (IMS) as the platform for convergence. By definition, IMS is access agnostic; it provides services and features through a common core network, regardless of the means of transport. However, the IMS standards are just beginning to address the challenges associated with interworking with existing cellular circuit networks. Achieving seamless mobility involves supporting both roaming and handoff between networks. This paper discusses the issues involved in providing seamless mobility for subscribers across the packet and circuit domains and proposes network-based solutions. © 2006 Lucen