Patent ID: 7529231

Claim:
A method of processing a Voice over Internet Protocol (VoIP) call from a first service provider to a destination telephone number, the destination telephone number served by a second service provider other than the first service provider, the method comprising: sending a Session Initiation Protocol (SIP) INVITE message from an originating switch to a first SIP server of the first service provider; determining an Internet Protocol (IP) address of a telephone number mapping (ENUM) server of the second service provider based on a carrier identification of the destination telephone number in order to receive a Uniform Resource Identifier (URI) from the ENUM server of the second service provider at the first SIP server, wherein the ENUM server of the second service provider is identified based on the carrier identifier and wherein the second ENUM server is configured to map the destination telephone number to the URI and to return the URI; querying, by the first SIP server, the ENUM server of the second service provider, and receiving the URI associated with the destination telephone number in response thereto; querying, by the first service provider, a Domain Name Service (DNS) server based on the URI, and receiving an Internet Protocol (IP) address of a second SIP server of the second service provider in response thereto; and using the first SIP server and the second SIP server to set up a bearer path for the VoIP call between the originating switch and a destination switch.