Summary:ASTERISK-10714: DTMF minimal duration and Recommendation Q.24
Reporter:Badalian Vyacheslav (slavon)Labels:
Date Opened:2007-11-08 01:38:16.000-0600Date Closed:2011-06-07 14:10:31
Versions:Frequency of

i see many messages like this
[Nov  8 10:15:23] DTMF[16622]: channel.c:2416 __ast_read: DTMF begin '4' received on SIP/
[Nov  8 10:15:23] DTMF[16622]: channel.c:2420 __ast_read: DTMF begin ignored '4' on SIP/
[Nov  8 10:15:23] DTMF[16622]: channel.c:2353 __ast_read: DTMF end '4' received on SIP/, duration 58 ms
[Nov  8 10:15:23] DTMF[16622]: channel.c:2403 __ast_read: DTMF end '4' has duration 58 but want minimum 80, emulating on SIP/
[Nov  8 10:15:23] DTMF[16622]: channel.c:2442 __ast_read: DTMF end emulation of '4' queued on SIP/

I see what many DTMF < 80ms... i go to google and find
ITU-T Q.24 : Multifrequency push-button signal reception

go to last page and see that recommended minimal signal duration = 40ms.
i change

and my clients is happy =)
Any comments?
Comments:By: Joshua C. Colp (jcolp) 2007-11-08 08:40:17.000-0600

This was discussed on the asterisk-dev mailing list a few months ago. Originally we had it set at 100ms but dropped it to 80ms after documentation and experience from others was provided to indicate that was the "best" duration.

By: Badalian Vyacheslav (slavon) 2007-11-08 08:49:12.000-0600

But we have recommendations (Table A, Q.24) and if some people write Soft (firmware to softphones) and looks to it - Asterisk and "some program" may not work prop.

If you think that 80ms its best value - its ok, but i think that if you up "minimal" value you delete some devices from * support list =)

Maybe discuss again? or its final value? =)

By: Joshua C. Colp (jcolp) 2007-11-08 08:52:42.000-0600

Why do we take devices off the supported list because of it? Asterisk will internally make sure the minimum duration of 80ms is met, and any device should accept that.

By: Badalian Vyacheslav (slavon) 2007-11-08 08:57:16.000-0600

stop. if duration < AST_MIN_DTMF_DURATION asterisk don't recognize it (in Transfer, WaitExten) and other. or i mistake?

By: Joshua C. Colp (jcolp) 2007-11-08 09:00:33.000-0600

You are mistaken. The Asterisk core will space out the DTMF a bit longer to meet the minimum duration, but it will still go to whatever on the channel (be it an application, or bridged channel). If this isn't happening then we need to figure out why as that is the real issue.

By: Badalian Vyacheslav (slavon) 2007-11-08 09:05:17.000-0600

ok. close bug... i try test this tomorrow with Transfer feature and reopen bug if can get information...

i start research it because many people in company if try transfer to 102 really transfer to 02 (very fast press 1 not recognize by *). 02 - its Police in Russia =) Clients that call to office was happy... police too! =)

By: Jason Parker (jparker) 2007-11-08 10:22:05.000-0600

Closing for now, per reporter.