Patent ID: 7408928

Claim:
A method of initiating a media call over a packet-switched network comprising:- (a) issuing a call set-up request at a first terminal having an address in a first address range, the call set-up request being destined for a second terminal in a separate network having an address in a second address range which overlaps with the first address range, (b) passing the call set-up request to a first call server communicatively coupled to the first address range, (c) passing the call set-up request from the first call server to a second call server communicatively coupled to the second address range, (d) causing the call servers to negotiate a port at each respective addresses of the terminals for subsequent communication once the call is set-up, (e) providing a first address translator having a first range address in the first address range, (f) providing a second address translator having a second range address in the second address range, (g) causing the first call server to provide the first terminal with the first range address of the first address translator as its destination address for the call, (h) causing the second call server to provide the second terminal with the second range address of the second address translator as its destination address for the call, (i) arranging for the first address translator to pass data received at the first range address from the first terminal at the negotiated port to the second address translator for onward communication to the address of the second terminal at the negotiated port, and (j) arranging for the second address translator to pass data received at the second range address from the second terminal at the negotiated port to the first address translator for onward communication to the address of the first terminal at the negotiated port, whereby two-way communication is established between the first and second terminals via the first and second address translators.