Patent ID: 7068647

Claim:
A method for performing IP telephony, comprising: receiving an identifier from the IP telephone; determining if the identifier is valid; and if the identifier is valid, assigning a range of port numbers to the IP telephone based on the identifier, wherein the IP telephone is operable to use at least a subset of the range of port numbers to send or receive IP communications; a Service Gateway receiving a data packet from the IP telephone, wherein the data packet comprises a private source IP address of the IP telephone, a source port number, and destination information associated with an IP device; the Service Gateway performing a network address persistent port translation (NAPPT) on the data packet, including storing translation information in a data structure, wherein the translation information comprises: the private source IP address of the IP telephone; a public IP address of the Service Gateway; and the assigned ports for the IP telephone; and the Service Gateway sending the data packet to the IP device.