[asterisk-bugs] [Asterisk 0012000]: snom DTMF duration detected wrong

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=12000 
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Reported By:                tbsky
Assigned To:                
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Project:                    Asterisk
Issue ID:                   12000
Category:                   Core/Channels
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     feedback
Asterisk Version:           1.4.18 
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Disclaimer on File?:        N/A 
Request Review:              
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Date Submitted:             02-15-2008 03:04 CST
Last Modified:              02-20-2008 14:47 CST
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Summary:                    snom DTMF duration detected wrong
Description: 
i use asterisk 1.4.18 and zaptel 1.4.8.  ip phone is snom 300 with firmware
7.1.30
the snom DTMF payload type is 101, and asterisk DTMF is rfc2833.
snom can not use DTMF.  asterisk will set the DTMF duration wrong.
please see snom-dtmf.txt

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 meric - 02-20-08 14:47  
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This is a SNOM bug.  I reported it to them months ago, but still haven't
seen a fix.

It seems that the first SIP INFO message sent (since the phone was booted)
contains an invalid duration.  Subsequent messages are ok.

The reason it doesn't affect SIP2SIP calls is that most SIP devices ignore
the duration field anyway.  It's a problem with PSTN calls via asterisk,
because asterisk uses the duration to generate the tones.

I went through the asterisk code a while back, and what it does is
suppress all other audio while in tone generation, which given the duration
provided by the SNOM phone is *quite* a while.  The result for the end-user
is a call which appears to have dropped out.

I've uploaded my crude workaround which clamps the DTMF duration on all
INFO messages.  It isn't something which belongs in Asterisk, but might be
useful as a temporary solution. 

Issue History 
Date Modified   Username       Field                    Change               
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02-20-08 14:47  meric          Note Added: 0082679                          
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