[asterisk-users] DTMF auto detection bug?

Joshua Colp jcolp at digium.com
Mon Apr 9 07:43:50 MST 2007

Arik Raffael Funke wrote:
> Hi,
> it seems that there is a bug in asterisk's dtmf mode autodetection. 
> Assume following sip.conf:
> [sipprovider]
> disallow=all
> allow=g726
> dtmfmode=auto
> DTMF does not work. It seems rfc2833 mode is chosen despite it being 
> obvious that this cannot work!

Why could it not work? While RFC2833 is carried over the RTP stream it 
is not sent in the audio stream so it should work as long as the remote 
end is using it.

> The following configuration is necessary to get DTMF to work: dtmfmode=info

It's always best to specify the dtmfmode in use as it controls both 
receiving and sending. The auto setting also does not encompass the info 
DTMF option for sending.

> In my opinion, this behaviour is counter-intuitive. I am using asterisk 
> 1.2. In v. 1.4 does dtmfmode=auto still have the behaviour?

I do not believe it has been changed at all. If you have a method of 
better determining things please feel free to share it.

> Cheers,
> Arik

Joshua Colp
Software Developer
Digium, Inc.

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