Patent ID: 7787441

Claim:
A communication system, comprising: a plurality of communication elements, comprising: a gatekeeper residing in a first network, a gateway connected to the gatekeeper, and a communication unit residing in a second network, the communication unit connected to the gateway, a request message is sent from the communication unit to the gatekeeper via the gateway in order to establish a trust relationship between the communication unit and the gateway, wherein the gateway checks the authenticity of the request message from the communication unit, wherein the gateway forwards the request message to the gatekeeper after the request message is verified as authentic, wherein the gatekeeper checks that the communication unit is authorized at the gatekeeper in response to receiving the forwarded request message, and wherein when the communication unit is authorized: the gatekeeper sends a first response message to the gateway indicating a positive authorization, and the gateway receives the first response message and sends a second response message to the communication unit in response to receiving the first response message, the second response message indicating a positive authorization, wherein the trust relationship is established between the communication unit and the gateway as a result of the request message being verified as authentic and of the communication unit being verified as authorized, and wherein the first communication network and the second communication network are different networks.