[Asterisk-Users] Missing 31 DTMF tones over ZAP

[Matt King]

Hello,

    I'm posting this to the list in case others run into the same issue.
   
    I've recently been connecting * to a legacy Avaya InDEX switch over 
E1 ISDN PRI here in the UK.  Everything was working OK, except that DTMF 
digits were not being recognised by * when sent by the Avaya switch to 
the * system.  Instead, the background noise of the call centre would be 
silenced while users hit the keys on their phones - echo tests and 
RecordFile produced a flatline response.

    I had at first thought that the Avaya switch may not be sending 
them, however this was working when * was not in the call path.

    With further testing, I've found out that it is in fact only the 
first 31 DTMF tones that are missing - those following are picked up 
OK.  I've got no idea why this should happen, and have kludged a fix by 
having the Avaya switch send out 31 'fake' tones before the user starts 
entering data (using Translation inside Route List).   If anyone has 
come across this before and knows of a 'proper' fix, or even what might 
be causing the issue, I'd be very grateful for the information.

    Hope this helps,

       Matt King, M.A. Oxon.
       Managing Director, Orderly Software Ltd.