[asterisk-users] duration of rfc2833 generated dtmf

[Mark G. Thomas]

Hi,

On Mon, Apr 13, 2009 at 05:32:45PM -0400, John covici wrote:
> Hi.  I have a SIP provider which wants RFC2833 for the dtmfmode,
> however I would like to increase the duration of the tone, its pretty
> short and some IVR's are unhappy or don't detect it.  I did poke
> around, but it looks like when RFC2833 is used, it actually generates
> rtp packets of some sort, so I have no idea how to increase that
> duration.
> 
> Any assistance would be appreciated.

I had a similar problem.

Adding "dtmf" to the "console =>" line in logger.conf is tremendously
helpful in diagnosing the dtmf behavior.

My successful work-around was to recompile asterisk with the following 
adjustments. Asterisk then extends the duration of the short tones. I'm
puzzled why these aren't a run-time configuration settings, since I'd
think this would be a common problem.

[root at sylvester asterisk-1.4.24]# diff main/channel.c_orig main/channel.c
91c91
< #define AST_DEFAULT_EMULATE_DTMF_DURATION 100
---
> #define AST_DEFAULT_EMULATE_DTMF_DURATION 150
94c94
< #define AST_MIN_DTMF_DURATION 80
---
> #define AST_MIN_DTMF_DURATION 150

I also later got my provider (Vitelity) to provision my service
on a different server of theirs, which then also seemed to improve 
both their RFC2833 DTMF reliability and duration.

-Mark

-- 
Mark G. Thomas (Mark at Misty.com)
voice: 215-591-3695
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