2Donkeys
If you're flying within ECAC (basically Europe) then you can file everything to Eurocontrol via SITA. Providing your message includes the AFTN addresses of any downroute, non-ECAC states, Eurocontrol will handle any further notification needed. Obviously, in this case, any AMD or REJ messages are responded to via SITA to your originator address.
If you're flying non-ECAC (or sometimes simply returning to ECAC states) you may need to file to the local tower/FIR of the departure airfield via AFTN. Your AFTN options are as follows:
1. Direct AFTN Connection provided by the CAA. This will be a leased line (running at max 9600). They provide/recommend the modem for your end and it can be connected to a PC and/or printer. With this option you'll have to provide some sort of receiving software that the CAA will want to vet.
2. 3rd Party Company provide the connection and software. There are a few of these around such as Copperchase, Stonefield Systems etc. They will provide an apparent AFTN connection but beware it's sometimes actually a telex line they're providing with switching onto the AFTN network.
3. Outbound AFTNs only. Assuming you've got a SITA connection, you can send outbound AFTNs via SITA. This involves sending a SITA message to a SITA/AFTN switch address which presents the message to AFTN for routing. The problem with this idea is that you don't get any incoming messages.
4. Telex. Both incoming and outgoing AFTNs can be routed via telex. Therefore if you've a telex line with appropriate software then it's technically possible to make it work.
I've not heard of an IP based AFTN solution yet but I'm sure it may be around or on the way soon. AFTN is still a necessary comm medium in many parts of the world and if you're flying to those places it really becomes a necessary evil. Also I think if your an operator, all air traffic message are free (but be careful with addresses starting with "H", they'll cost you an arm and a leg).
Hope the above helps....
FPM