An apparatus configured to operate as a Service Centralization and Continuity Application Server (SCC-AS) within an IP Multimedia Subsystem network, the apparatus comprises a receiver for receiving a SIP INVITE originating from or sent via an access domain and for determining that the INVITE relates to a handover of a User Equipment (UE) currently served by the SCC-AS, to that access domain and for which a session with a peer UE is ongoing and the apparatus further comprises a message handler for determining if capabilities for the ongoing session, identified within said INVITE, have changed with respect to capabilities previously associated with the ongoing session and, if it is determined that capabilities have changed, for causing a SIP message to be sent to said peer UE, the message containing the changed capabilities.