Enabling roaming management in GPRS and WLAN networks based on SIP

In the wireless networks technologies, the concept of Next Generation Networks (NGN) focuses on environments in which IP technology provides transparent connectivity. It includes the roaming and mobility management between mobile users in heterogeneous networks. We compare two roaming models in order to integrate communication and session control from GPRS to WLAN 802.11 using SIP signaling protocol. The approaches follow the classification for service composition of the SAHARA project: Cooperative Model and Brokered Model. The solutions are based on loose coupled integration and IP mobility, which provide mobile applications and mobile services. Contributions include the selection of the better model, the design of SIP broker agent and the implementation of roaming management following the IETF specifications.