Seamless convergence of existing wireline/wireless networks using IP Multimedia Subsystems (IMS)

Wireless Service Providers want to introduce compelling new services that rapidly generate revenue - starting with seamless voice convergence. Seamless voice convergence gained a lot of momentum in the Service Provider industry. Seamless voice convergence is enabled through the interworking of cellular service and Wi-Fi domains. This converged voice service, or Dual Mode Service (DMS), which allows a subscriber to seamlessly access services while moving between Wi-Fi and cellular networks using a dual mode handset (DMH). Roaming and handoff between the cellular and Wi-Fi domains form the central parts of any dual mode service. However, in our view, we believe that a Dual Mode Service solution must go further than only addressing the end-user needs to improve reachability when subscribers are located in the home and roaming in/out of the cellular environment. This voice convergence solution must offer subscribers a new range of hot communication services that enhance the value of the user experience. This can be achieved by building dual mode service solution based on the IP Multimedia Subsystem (IMS), which is an open, standards-based solution for delivering advanced communications services over IP networks. Several architectures have been proposed to develop Dual Mode Service solution. In this paper, we show several architectures approaches in designing DMS and report our experiences designing, and integrating a carrier-grade DMS based on an IMS architecture that overcomes many limitations found in other solutions. We compare these solutions with respect to cost, efficiency, and the benefits for service provide and end user.