Patent ID: 8665864

Claim:
A method for session establishment, the method comprising, in order: a network gateway receiving a first session initiation message, wherein the first session initiation message defines a request from a source client device seeking to establish a session with a destination client device, wherein the first session initiation message contains a first endpoint identifier, wherein the first endpoint identifier is associated with the destination client device, wherein the first session initiation message is an Integrated Service Digital Network User Part (ISUP) Initial Address Message (IAM), and wherein the source client device is a circuit-switched network client device and the destination client device is a packet-switched network client device; the network gateway translating the first endpoint identifier to a second endpoint identifier without performing any address translation database lookup for the translating, wherein the first endpoint identifier is a Public Switched Telephone Network (PSTN) number and the second endpoint identifier is a Voice over Internet Protocol (VoIP) address comprising at least the PSTN number and a suffix, wherein the suffix comprises an “@” followed by a predefined domain name, and wherein the network gateway translating the first endpoint identifier to the second endpoint identifier without performing any address translation database lookup for the translating comprises the network gateway translating the PSTN number to the VoIP address by adding at least the suffix to the PSTN number; the network gateway generating a second session initiation message, wherein the second session initiation message contains the second endpoint identifier; and the network gateway transmitting the second session initiation message to a network element serving the destination client device, to facilitate establishment of the session between the source client device and the destination client device, wherein the session is a call, and wherein the second session initiation message is a Session Initiation Protocol (SIP) INVITE message.