Patent ID: 8499344

Claim:
A communications system for making a multimedia call, comprising: a first multimedia terminal configured to communicate using H.323; a second multimedia terminal configured to communicate using H.323; a first communication unit, associated with the first multimedia terminal, configured to establish a multimedia call over a shared IP network between said first multimedia terminal and the second multimedia terminal using H.323, said communication unit including a first firewall through which the multimedia call passes, wherein the first firewall is configured to restrict certain types of communication between the first terminal and the shared IP network, each of the first multimedia terminal and the second multimedia terminal has a number of logical communication ports for transmitting or receiving the multimedia call, including at least one dynamically assigned port; and a transmitter, associated with the first multimedia terminal is configured to send a request to the second multimedia terminal to open up one or more dynamic ports in the second multimedia terminal; a proxy server disposed between the first multimedia terminal and the second multimedia terminal that is configured to act as a proxy for the first multimedia terminal and the second multimedia terminal during the multimedia call, wherein the proxy server has logical communication ports for communication with the first multimedia terminal, including one or more pre-assigned ports for communication with the first multimedia terminal; the first firewall is configured not to restrict communication between the first multimedia terminal and the one or more pre-assigned ports of the proxy server for communication with the first multimedia terminal, and the proxy server is configured to receive the request to open up said one or more dynamic ports in the second multimedia terminal via one of the proxy server's pre-assigned ports and to modify the request to change a source of the request from a network address of the first multimedia terminal and the at least one dynamically assigned port of the first multimedia terminal to a network address of the proxy server and a pre-assigned port of the proxy server for communication with the second multimedia terminal.