Inter-Working Between a Packet-Switched Domain and a Circuit-Switched Domain

摘要

The present invention proposes a solution for providing packet-switched services to a user, even in case the user is accessibly only via a circuit-switched access. For this purpose it is proposed to force the user to report changes in the reachability status and to keep the user's registration alive in a packet-switched domain as long as the user is reachable. A packet-switched adapter located between the circuit-switched domain and a packet-switched domain aligns the registration status of the user in the packet-switched domain to the reachability status and performs a registration procedure depending on the outcome of the alignments. The registration procedure might be in detail either a registration or a re-registration or a de-registration procedure.