I am resurrecting a project planned for a couple of years ago, and discussed briefly here at that time, to implement a Radio-over-IP module for FreePBX that will add the capability, administered by FreePBX, of tying our Civil Air Patrol wing’s PBX into its radio network. That project was placed on the back burner at the time and is now taking shape again.
Our CAP wing has a PBX, based on the ancient AsteriskNOW 2.0.2 and soon to be upgraded to AsteriskNOW 612. The server is located in my home and there are several dozen phones implemented around the state, most of which are at Wing HQ about 35 miles from here, and the rest in members’ homes. The phones are mostly Grandstream GXP1400 with a few of a different model, and some smartphone VoIP apps and XLite softphones. The SIP protocol is used exclusively.
The objective is that anyone can pick up one of those phones and dial a 3-digit number, and be connected to an HF SSB channel to communicate with ground teams in the field anywhere in the state, or a VHF ground-to-air channel to communicate with aircraft.
I would like to implement this as a FreePBX module, to be administered with FreePBX Admin->Module Admin, and show up under Applications->Extensions or something else under Applications, like Applications->RoIP.
I know there are several solutions out there that involve dedicated Asterisk installations for RoIP, mostly directed to the amateur radio community, implementing things like VoIP/RoIP repeaters and hybrid radio/IP networks. I have looked at all I can find, and installed a couple of them in VirtualBox virtual machines, and so far haven’t seen a clean way to migrate to an existing AsteriskNOW / FreePBX installation. But, that’s probably just because I don’t (yet) know anything about Asterisk modules and how to implement / integrate them.
Regarding how to implement PTT, I’m not sure yet. The easiest approach from the user’s perspective would be to implement a VOX approach, but that would be subject to the varying levels of background noise (which could be quite high) in an event-management environment in a room full of people all yelling at one another. The other approach would be to force the phone user to punch a set of keys to switch the remote transmitter between transmit and receive, perhaps “*” for transmit and “#” for receive.
Any thoughts on how best to approach all of this would be much appreciated.
Thanks…
Eric