Patent ID: 7606202

Claim:
A method for offloading call control services from a first network of a first protocol type to a second network of a second protocol type, the method comprising: at a call control offload function implemented at a network routing node: receiving a query message in response to a switching office detecting a call originating from a calling party in a first network of a first protocol type; in response to receiving the query message: determining routing information for a node in a second network of a second protocol type different from the first protocol type based on information identifying the calling party; and offloading call control services to the second network using the node, wherein the node in the second network comprises an IP multimedia subsystem (IMS) call session control function (CSCF) that facilitates providing of the call control services using nodes in the second network, wherein offloading the call control services includes providing the routing information to the switching office and so that the switching office can use the routing information to offload the call control services.