NAT traversal in VoIP communication system

摘要

Methods, systems, and apparatuses are provided for VoIP communication with endpoint devices via a network address translator (NAT). A plurality of proxy servers is configured to relay communications through mapped paths of the NAT during operations including VoIP sessions through or with the plurality of endpoint devices and during other operations not involving VoIP sessions through or with the plurality of endpoint devices. The mapped paths are susceptible to being unmapped by the NAT if the mapped path is unused for a threshold duration of time. The proxy servers maintain the mapped paths through the NAT by prompting the endpoint devices to communicate data to the plurality of proxy servers. A call control server uses a selection algorithm to select a particular one of the proxy servers to be used for routing communication of a VoIP session between endpoint devices.