Keys press not being detected when on call

FreePBX: 2.10.58

Hi All,

I have a few Aastra 9143i phone and the users have mentioned when they are on a call and are presented with a list of options, press a key it is never detected on the other end.

Can anyone suggest what this could be? I gather is either the phones or a misconfiguration of freepbx (most likely).

Many thanks,

What DTMF method are you using?


And passing DTMF is rarely an internal problem asterisk will happily and correctly transcode to what you send to the upline provider, you need to look at how your carrier supports the various DTMF methods,


in the trunk is normally recommended, unfortunatley many SIP carriers get it wrong.

Try sequencially

dtmfmode=rfc2833 ; best choice
dtmfmode=info ; sometimes needed
dtmfmode=inband ; only works on g711 codec

otherwise, if none of these work then start to bitch at your carrier.

You can add dtmf to your /etc/asterisk/logger.conf file for the “full” or “console” file if you want for fuller diagnostics.

thanks for the replies guys.

ummmm, pains me to say but where can I find this out and change?

BTW - this is on analog lines.

It goes in your outbound trunk settings. You might try the conveniently named “documentation” link on this age (twice) or maybe google it?

thanks dicko - I figured would be in outbound trunks but as the trunk is “ZAP Trunk (DAHDi compatibility Mode)” I am a little lost. I’ll go through the documentation and see what I can find.

thanks again for the info. much appreciated.

Dahdi always uses inband dtmf you could add
Toneduration=250 or something but also tume your tx rx levels

thanks dicko - seem to have sort have done the trick; I think I just need to play around with the duration value a little more but it now detects the correct key around half the time.

If 250 is not enough , the normal requirement is 60 milliseconds of pure tone at 0db relative, then check your 2/4 wire hybrid settings,(tx/rx settings) echo can upset everything . . .