IAX uses a single User Datagram Protocol (UDP) data stream between endpoints for both the session signaling and the media payloads. Thus it uses only a single UDP port number, typically 4569. This feature provides benefits for traversing network address translators on network boundaries, as it simplifies firewall configuration. Other VoIP protocols typically use independent streams for signaling and media, such as the Session Initiation Protocol (SIP), H.323, and the Media Gateway Control Protocol (MGCP), which carry media with the Real-time Transport Protocol (RTP).