Method and system for realizing session handover

A system for realizing session transfer, comprising:

• a service continuity application server (SCC AS) and an enhanced mobile switching center (eMSC), wherein,
• the SCC AS is configured to:
• after receiving a transfer request, when judging that a state of a session needed to be transferred is a held state, update a remote leg by using a held state session state information, and notify the eMSC that the state of the session needed to be transferred is the held state;
• and
• the eMSC is configured to:
• when acquiring that the state of the session needed to be transferred is the held state, complete a call setup of a target access network according to the held state,
• wherein, the SCC AS is configured to notify the eMSC that the state of the session needed to be transferred is the held state by the following method:
• when judging that the state of the session needed to be transferred is the held state, rejecting the session transfer request, replying a rejection message carrying the held state session state information to the eMSC, and notifying the eMSC that the state of the session needed to be transferred is the held state;
• or
• when judging that the state of the session needed to be transferred is the held state, and before replying a rejection message to the eMSC, notifying the eMSC that the state of the session needed to be transferred is the held state by carrying the held state session state information in a temporary response message or a notification message;
• after updating the remote leg, replying an acknowledgement message carrying the held state session state information to the eMSC, and notifying the eMSC that the state of the session needed to be transferred is the held state.