InterAsterisk eXchange

from Wikipedia, the free encyclopedia
IAX2 in the TCP / IP protocol stack :
application IAX2
transport UDP
Internet IP ( IPv4 , IPv6 )
Network access Ethernet Token
bus 		Token
ring 		FDDI ...

Inter-Asterisk Exchange ( IAX ) is a network protocol that from the open source - PBX Asterisk is used. It is used both for the connection between individual Asterisk servers and for communication with end devices, with which Voice-over-IP calls are possible. Version 2 (IAX2) is currently used.

Other standards for IP telephony are the widely used SIP and H.323 .

In contrast to some of the other VoIP protocols, IAX / IAX2 offers advantages in IP telephony because the protocol used is less complicated. In detail: Only one port is required for the signaling process and for the transmission of the audio stream (port 4569). The IAX protocol does not usually have any NAT or firewall problems as they occur when using SIP or H.323: Clients that register on the server can keep the connection open. If the server is behind a firewall, the port can be forwarded.

Due to the smaller overhead of the IAX / IAX2 protocol - compared to SIP or H.323 - in combination with a narrowband codec , such as B. GSM , iLBC or G.729 , even VoIP connections possible via an analog modem (with a data transfer rate of approx. 38 kbit / s in the send direction).

The goals of IAX

The following properties were the main goals in the development of IAX:

  • the bandwidth used for multimedia transmission should be as small as possible
  • special attention was given to the control of the transmission and a single voice connection
  • a NAT -support should already be installed

IAX can therefore transmit control signals and several calls or video messages between two computers or end devices via a single UDP connection. IAX is a binary protocol that makes very good use of the bandwidth. In a few places, Mark Spencer , the creator of the protocol, has decided to use a little more total bandwidth, but to be more efficient in one-on-one conversations.

IAX clients

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hardware

  • Digium IAXy
  • Virbiage 3010 (also sold as the Freshtel 3010 and the Tesco IPA 1000)
  • ALLNET VoIP phone with SIP and IAX2 ALL7960
  • CriticalLinks edgeBox telephone system, Radius server and router with SIP and IAX edgeBox
  • Snom Voip Phone snom.com

software

  • Diax ( Freeware , for Windows) - current version 0.9.15a from 2005
  • IAXComm ( Open Source , for Linux, Mac OS X and Windows) - current version 1.2. from 2006
  • IAXPhone ( Crippleware , for Windows)
  • Zoiper, formerly Idefisk (Crippleware, free version only for non-commercial use, for Linux, Mac OS X, Windows and Android) - current version 5
  • Kiax (Open Source, for Linux and Windows) - current version 2.1 Beta2 from 2009
  • LoudHush (Crippleware, for Mac OS X)
  • PURtel (permanently set to PURtel, Windows)
  • YakaPhone (Open Source, for Windows) - last version from 2016
  • Yate (Open Source, Server and Client) - current version 6.1.0.1 from 2018
  • ZiaxPhone (Freeware, for Sharp Zaurus )

Web links