Patent ID: 8477720

Claim:
A method of selecting an access domain for sending information between a wireless terminal and a core network, wherein sessions between the wireless terminal and the core network are established and controlled using an IP Multimedia Subsystem (IMS), the method comprising: maintaining within the IMS, a database holding information on real-time packet-switched service capabilities of a plurality of access domains; at or in response to IMS registration of the wireless terminal, interrogating said database by an IMS node based upon information received from the wireless terminal identifying currently used or available access domains to retrieve capabilities information for the currently used or available access domains; sending the capabilities information for the currently used or available access domains from the IMS node to the wireless terminal; determining by the wireless terminal, whether a packet-switched access domain that supports packet-switched handover is available; when a packet-switched access domain that supports packet-switched handover is available, registering by the wireless terminal first with the available packet-switched access domain and second with the IMS; and when a packet-switched access domain that supports packet-switched handover is not available, roaming into an access domain having the best radio signal strength and initiating registration with the IMS.