IAX: Inter-Asterisk eXchange Version 2
This document describes the Inter-Asterisk eXchange protocol, Version 2, an application-layer control and media protocol for creating, modifying, and terminating multimedia sessions over Internet Protocol (IP) networks. IAX is targeted primarily at the control of Voice over Internet Protocol (VoIP) calls, but can be used with streaming video or any other type of multimedia. IAX is an "all in one" protocol for handling multimedia in Internet Protocol (IP) networks. It combines both control and media services in the same protocol. IAX's compact encoding decreases bandwidth usage and since IAX uses a single, static, UDP port, it facilitates native support for Network Address Translation (NAT) transparency. IAX is well suited for Internet telephony service, but, is open enough to support additional services.