Hang up on Dial Tone

I have asterisk and a TDM400 FXO card.

The incoming phone line appears to use a non-standard method to indicate the phone has been put down. Instead of giving a busy signal, it gives a (UK) dial tone for a few seconds before going silent.

Is there anyway I can detect this, and hang up?


are you in the UK ? are you not getting a polarity reversal on remote hangup ?

I am in the UK, but I am connected to a line from a Nortel Meridian PBX, rather than directly to a BT line. I have tried enabling hangup on polarity reversal, but this does not work.

This is why I want to hang up on dial tone - this is what I get from the line on hang up.

lookup ‘loadzone’ and ‘progzone’, and maybe callprogress (can be flaky)

I set progzone to uk and modified the busy signal in indications.conf to be the same as the dial tone (on the building’s PBX they are the same), but still no joy.