Handover

A mobility controller capable of assisting handover of a user equipment from a first radio access network to a second radio access network, the second radio access network being coupled to the mobility controller and having an association with the first radio access network, and the first and second radio access networks being capable of communication with a session transfer controller, the mobility controller being arranged to:

• receive a first message from the first radio access network requesting handover of the user equipment to the second radio access network;
• send a second message to the session transfer controller subscribing the mobility controller to status updates originated by the session transfer controller, said status updates relating to a status of a call to or from the user equipment;
• receive one of said status updates at the mobility controller originated by the session transfer controller, dependent on a communication via the first radio access network from the user equipment to the session transfer controller of a change in the status of said call;
• and
• in response to receipt of said status update, update a call status indicator of the mobility controller to synchronize the call status in the mobility controller with that of the user equipment in support of continuity of the call on handover of the user equipment to the second radio access network.

A session transfer controller capable of assisting handover of a user equipment from a first radio access network to a second radio access network, the second radio access network being coupled to a mobility controller and having an association with the first radio access network, and the first and second radio access networks being capable of communication with the session transfer controller, the session transfer controller being arranged to:

• receive a second message originated by the mobility controller subscribing the mobility controller to status updates originated by the session transfer controller, said status updates relating to a status of a call to or from the user equipment;
• receiving a communication from the user equipment indicating a change of status of said call;
• and
• dependent on the receipt of the second message and said communication, originate one of said status updates to the mobility controller.