A method and apparatus for maintaining service continuity for User Equipment accessing an IP Multimedia Subsystem communication network. A routing identifier is established that identifies a Service Centralization and Continuity Application Server allocated to the User Equipment. The routing identifier is sent to the User Equipment. In the event of disruption to the service between the User Equipment and the Service Centralization and Continuity Application Server, a handover message is sent from the User Equipment via a Circuit Switched access network. The handover message includes the routing identifier, and is then forwarded to the identified Service Centralization and Continuity Application Server. This allows the same Service Centralization and Continuity Application Server to be used after the handover as was used before the handover, thereby providing service continuity.