Patent ID: 8761160

Claim:
A method, performed in a session border controller, of establishing Internet Protocol (IP) telephony sessions between enterprises, the method comprising: learning a route path for reaching a first enterprise from a second enterprise, the first enterprise and the second enterprise both belonging to a federation and obtaining IP telephony services from the same service provider, wherein the service provider comprises a Public Switched Telephone Network (PSTN) gateway that provides telephone calls from the first enterprise to a PSTN; identifying an IP telephony session as a federated communication, wherein the IP telephony session is between a first communication device of the first enterprise and a second communication device of the second enterprise; and tagging the identified IP telephony session so that the identified IP telephony session traverses the learned route path, wherein the tagging indicates a federated communication and wherein the learned route path bypasses the PSTN gateway; wherein learning the route path comprises receiving at the session border controller located at the service provider a watcher event comprising a list of associated enterprises and session initiation protocol (SIP) headers comprising a route traversed by the watcher event, and parsing the SIP headers to determine the route path from the second enterprise to the first enterprise; wherein the first enterprise is coupled to the service provider via a first pair of session border controllers and a first SIP trunk, and the second enterprise is coupled to the service provider via a second pair of session border controllers and a second SIP trunk.