TDM400P with G-Tel 909 Payphone (USA model). RX Call detect

Hi Guys, I’m trying to get a G-Tel Model 909 (Star Telephone co Model 909) payphone working on my TDM400P card under Asterisk.

It will work with outgoing calls but doesn’t recognise incoming.

The phone rings, and if I pick up the receiver, I can hear the other side but they can’t hear me. The phone then hangs up some 6 seconds later thinking the receiver has been lifted for an outgoing call.

If I plug the phone into a normal ATA it works fine for incoming.

I assume it’s something to do with the chan_dahdi.conf file settings?

Anyone want to make a guess on settings? Also how do I reload the settings? I assume reload from the asterisk CLI just won’t cut it in this instance?

My guess is it’s something to do with signaling?

Even though the phone rings on an incoming call, it does not realise that an incoming call has happened. Something to do with line level or line signaling maybe?

If anyone can point me to better documentation on what all the options do in Chan_dahdi.conf it might help.

The phone works on a normal PSTN line. It does not require any special signaling etc like some payphones do.