Patent ID: 7257837

Claim:
A method of operating a proxy server for establishing a real time streaming media session between a first client served by the proxy server, the first client having been assigned an IP address which is a local area network address, and a second client served by a second proxy server, the method comprising: receiving an invite message from the first client over an internet protocol channel, the invite message including session description protocol fields identifying the IP address assigned to the first client and a unique identifier of the second client; comparing a source IP address extracted from the internet protocol channel to the IP address assigned to the first client; if the IP address extracted from the internet protocol channel does not match the IP address identified in the session description protocol fields, providing identification of a relay server resource to each of the first client and the second client by: sending a relay server invite message to a relay server; receiving a relay server response message, the relay server response message identifying a relay server resource, comprising a relay server IP address and port number, from a relay server; sending a redirect invite message to a redirect server, the redirect message including the identification of the second client; receiving a redirect server response message, the redirect server response message including a network address of the second proxy server serving the second client; sending a forwarding invite message to the network address of the second proxy server, the forwarding invite message comprising session description protocol fields identifying the relay server resource; receiving an OK response message from the second proxy server; sending, in response to receiving the OK response from the second proxy server, a second OK response to the first client, the second OK response comprising session description protocol fields identifying the relay server resource.