Patent ID: 8566405

Claim:
A session control method in a Converged Internet Protocol (IP) Messaging (CPM) server for supporting a CPM session between a first client subscribing to a CPM service and a second client not subscribing to the CPM service, the session control method comprising the steps of: receiving, after the CPM session is initiated between the first and second clients through the CPM server and at least one first Interworking Function (IWF) of a plurality of IWFs is selected, a session modification request message including specific media from the first client, the CPM session including a first session supporting at least one first media; sending the session modification request message including the specific media to the at least one first IWF through the initiated CPM session; and receiving an acceptance response message from the at least one first IWF, the acceptance response message including information indicating that at least one second media is supported by the at least one first IWF and at least one third media is unsupported by the at least one first IWF; modifying the first session to include the at least one first media and the at least one second media; and initiating a second session including the at least one third media unsupported by the at least one first IWF with at least one second IWF.