Chapter 5. SIGNALING AND MEDIA: IAX SECURITY

Inter-Asterisk eXchange (IAX[2]) is a protocol used for Voice over IP (VoIP) communication with Asterisk servers (http://www.asterisk.org/), an open source PBX system. Along with Asterisk servers, IAX can be used between any client endpoint[3] and server system supporting the IAX protocol for voice communication.

IAX is much simpler than other VoIP protocols such as H.323. For instance, IAX uses a single UDP port (port 4569) between all endpoints and servers. This feature makes IAX very attractive for firewall administrators, who are often asked to open many ports higher than 1024 for VoIP communication. Additionally, IAX provides for both signaling and media transfer within the protocol itself, while ...

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