Patent ID: 7593388

Claim:
A communication system comprising: a plurality of virtual private networks ‘VPNs’ interconnected by a first data network; a second data network connected to the plurality of VPNs via the first data network, the second data network using a network addressing scheme that is different to a network addressing scheme used by at least one of said plurality of VPNs; a VPN gateway interfacing the first data network and a call server in the second data network, the VPN gateway being configured to pass communication session signaling traffic between an entity in one of said plurality of VPNs and the call server for establishing a communication session between said entity in one of said plurality of VPNs and an entity in an external Time Division Multiplex ‘TDM’ network, said external TDM network handling communication session bearer traffic in a TDM format different to a packet data format of the first data network; and a VPN converter interfacing the first and second data networks and directly interfacing the first data network to said external TDM network, the VPN converter being configured to receive bearer traffic relating to said communication session established between said entity in one of said plurality of VPNs and the entity in the external TDM network and to convert said bearer traffic between the packet data format of the first data network and the TDM format used in the external TDM network.