Patent ID: 7450565

Claim:
A method of setting up a call between first and second nodes of a communication system, said call extending across a circuit switched access network available to the first node and a packet switched backbone network, the networks being interconnected by at least one Media Gateway, the method comprising: 1) sending a call initiation message from the first node to the second node via a control node over a packet switched access network available to the first node; 2) at the control node, obtaining from a Home Subscriber Server the identity of a Media Gateway Control Function controlling that Media Gateway which will terminate the circuit switched call for the first node; 3) establishing a circuit switched call between the first node and said Media Gateway; 4) sending from the control node to the first node over the packet switched access network, a circuit switched access number associated with the identified Media Gateway Control Function; 5) calling said access number from the first node, and as part of the call set-up procedure communicating the identity of the Media Gateway selected to terminate the call to the Media Gateway Control Function; 6) terminating the circuit switched call at the selected Media Gateway; and 7) sending an update message from the first node to the second node over the packet switched access network, the Media Gateway Control Function incorporating into the update message an IP address of said selected Media Gateway.