Method and apparatus for supporting communications between a computing device within a network and an external computing device

Abstract

A network communication bridge establishes communication between a computing system within a protected network and an external computing system. A registrar is positioned outside the protected network and registers authorized users. The registrar determines if the computing device associated with the user is publicly addressable, and for those computing devices that are not publicly addressable, the computing device maintains a persistent communication session with a bridge proxy server. The bridge proxy server employs a reversal or relaying technique to enable communication between two systems that cannot ordinarily establish communication with each other, based on characteristics of the two systems. If at least one party to a communication is publicly addressable, then a reversal technique is employed. If neither party to the communication is publicly addressable, then both parties have a persistent session with their respective bridge proxy server, and the bridge proxy server acts as a 'relay service' for communications between the initiator and the recipient. The invention can be implemented as a separate application or as an enhancement to the Session Initiation Protocol (SIP).