A private communications network and method of managing calls in a private communications network. A Session Border Controller (SBC) listens for private network voice communications originating from private communications devices, e.g., Session Initiation Protocol (SIP) devices sending/receiving Voice over Internet Protocol (VoIP) communications such as SIP messages. The SBC assigns a unique port to each registering communications device and adds a path header with a single, common SBC port to the SIP register messages. A softswitch responds by adding a route header to identified voice communications. Thereafter, all identified voice communications pass through a single, common SBC port.