Editing Aeronautical Fixed Telecommunication Network (section)

== Communications infrastructure ==
The original AFTN infrastructure consisted of landline [[teleprinter]] links between the major centers. Some long distance and international links were based on duplex [[radioteletype]] transmissions and leased lines. When it upgraded to [[CIDIN]] (Common [[ICAO]] Data Interchange Network), it was upgraded to [[X.25]] links at much higher data rates. As the [[Aeronautical Message Handling System]] (AMHS) comes online over the next decade, it will switch to [[X.400]] links, with either dedicated lines or [[Tunneling protocol|tunneled]] through IP.{{when|date=August 2012}}

[[IWXXM]] messages are lengthy and contain characters not supported by AFTN, so cannot use AFTN equipment. IWXXM requires the use of AMHS for international exchange.<ref name=":02">{{Cite journal |last1=Latifiyan |first1=Pouya |author-link=Pouya Latifiyan |last2=Entezari |first2=Mojtaba |date=March 2024 |title=IWXXM Amendment (ICAO Meteorological Information Exchange Model) |journal=CATC Robex and Statics Conferences - 2024 |language=En |location=Tehran, Iran |publication-place=Tehran, Iran |pages=49 |doi=10.13140/RG.2.2.12572.30088 |quote=IWXXM messages are lengthy and contain characters not supported by AFTN, so cannot use AFTN equipment. IWXXM requires the use of AMHS for international exchange. |doi-access=free}}</ref>