[asterisk-users] DTMF tones in MixMonitor recording

[Joshua Colp]

On Mon, Apr 30, 2018, at 11:23 PM, Patrick Wakano wrote:
> Hello list,
> Hope you are all doing fine!
> 
> I have stumbled over some piece of dialplan code in which apparently they
> were trying to avoid recording the DTMF tones in the wav file. It is really
> messy and I am not sure if this really works. So after a bit of research I
> found this comment (
> https://community.asterisk.org/t/asterisk-dtmf-record/65040) in which it is
> said:
> 
> *"Asterisk strips the DTMF from the audio stream when configured for
> inband, so internal stuff can react to the DTMF and so the other side does
> not hear the tone unless they are using inband (in which case it is
> regenerated)"*
> So my questions are, what are the cases in which Asterisk regenerates the
> DTMFs? Does it cause the recording to have the tone as well, or is it only
> transmitted to the other leg without being generated to the recording file?
> Also, what if one or both legs are RFC2833? From my tests the RFC2833
> events never show up in the recording, but I just want to confirm that this
> is always true.

If properly configured then Asterisk will always strip and regenerate the DTMF tone. You have to purposely misconfigure things to cause it to not get stripped. IE: DTMF is actually inband but you configure it for RFC2833. Since Asterisk wouldn't be listening to the audio stream, it would go right through and get recorded.

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org