[asterisk-bugs] [Asterisk 0013917]: [patch] fxo modules incorrectly believes channel is answered, if telco reverses line polarity at off hook.

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=13917 
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Reported By:                alecdavis
Assigned To:                
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Project:                    Asterisk
Issue ID:                   13917
Category:                   Channels/chan_dahdi
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     confirmed
Asterisk Version:           SVN 
Regression:                 No 
SVN Branch (only for SVN checkouts, not tarball releases):  trunk 
SVN Revision (number only!): 155671 
Request Review:              
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Date Submitted:             2008-11-18 01:22 CST
Last Modified:              2009-02-09 17:20 CST
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Summary:                    [patch] fxo modules incorrectly believes channel is
answered, if telco reverses line polarity at off hook.
Description: 
With answeronpolarityswitch=yes in chan_dahdi.conf
In our setup channels 63-65 in attached chan_dahdi.conf

When fxo modules are connected to analog lines that reverse polarity when
the line is picked up, the fxo driver (wcdtm) sends a polarity reversal
event, causing the channel to be answered, which is incorrect, as the call
is yet to be dialled.

The caller hears a very short ring, then silence for a while as the call
is set up, then finally remote ringing. This is very off putting for the
unaware user.

The attached patch chan_dahdi.diff.txt patch, sets the polaritydelaytv at
call setup, then uses the same sytle of checking mechnism as is used for
hanguponpolarityswitch=yes.

The DAHDI_EVENT_POLARITY in dahdi_handle_event has been reworked, from
using IF/ELSE statements with multiple OR's to easier to read SWITCH
statements.

Has been on a production box for nearly a month with around 100 calls out
of the fxo channels a day, with clean sounding ringing, with audio passed
as soon as the called party answers.



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Relationships       ID      Summary
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related to          0013716 [patch] Prevent false answer of channel...
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 (0099769) alecdavis (reporter) - 2009-02-09 17:20
 http://bugs.digium.com/view.php?id=13917#c99769 
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please remove chan_dahdi.bug13917.diff.txt
uploaded chan_dahdi.bug13917.feb09.diff.txt

Updated to trunk today, and the old patch chan_dahdi.bug13917.diff.txt
doesn't apply clean. 

Issue History 
Date Modified    Username       Field                    Change               
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2009-02-09 17:20 alecdavis      Note Added: 0099769                          
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