Method for NAT traversal in a P2P-SIP network

摘要

The invention concerns a communication system comprising a user agent (tim) and a network address translation helper function (NHFt), the network address translation helper function comprising a directory for advertising user agents (alice), the network address translation helper function comprising furthermore a signaling protocol unaware, stateless transport layer relay for forwarding packets, where the user agent (tim) comprising keeping means to maintain the connection between the user agent (tim) and the network address translation helper function (NHFt). The invention concerns also a method for inviting a user agent comprising the steps of advertising the user agent (alice) at a network address translation helper function (NHFt) of an other user agent (tim) that maintains a connection path between the network address translation function (NHFt) and itself; Inviting the other user (tim) agent by directing the signaling flow comprising the invitation messages to the network address translation helper function (NHFt) without invoking further signaling elements; and forwarding the signaling flow directly on the maintained connection path to the other user agent (tim) without invoking further signaling elements.