There are lots of information about Type-B messages sent by airlines on IATA website but they have not stated under what communication systems (cable, teletype, intranet, internet, etc.) these messages are exchanged. What are these systems?
1 Answer
It's not just one. Private networks are used such as the IP-based ARINC AviNet, AFTN Teletype, etc.
For the specifics and standards, that information is not freely available (>\$3000). From IATA manuals, go to the Passenger tab, then the Security & Facilitation section. Or click here.
IATA's Passenger Data Exchange Support Plus package provides governments with all necessary standards, helpfully grouped in a single purchase.
The following example is for France (may not be current):
There is also a presentation on the IATA website you may want to download and check.