Patent ID: 8218531

Claim:
A non-transitory computer-readable storage medium in an originating Serving Call Session Control Function comprising computer instructions for: querying a Telephone Number Mapping system to provide contact information associated with a communication device; and receiving from the Telephone Number Mapping system the contact information for the communication device and a contact information for a terminating Serving Call Session Control Function assigned to the communication device, wherein the contact information of the communication device comprises at least one of a domain name or an Internet Protocol address associated with the communication device, and wherein the contact information of the terminating Serving Call Session Control Function comprises at least one of a domain name or an IP address associated with the terminating Serving Call Session Control Function, wherein the originating Serving Call Session Control Function receives an assignment from a Home Subscriber Server, wherein the Telephone Number Mapping system provides the originating Serving Call Session Control Function the contact information for the terminating Serving Call Session Control Function, such that the Telephone Number Mapping system has the same contact information available in the Home Subscriber Server for the terminating Serving Call Session Control Function, and wherein when the contact information for the terminating Serving Call Session Control Function is provided by the Telephone Number Mapping system, the Telephone Number Mapping system avoids a query to the Home Subscriber Server during a call process to reduce the workload of the Home Subscriber Server, reduce latency time for call setup, and reduce the number of Home Subscriber Server clusters in an IP Multimedia Subsystem network.