[asterisk-bugs] [Asterisk 0017400]: Writeformat Slin instead Alaw after attendend Transfer when using Answer before Dial without Moh

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=17400 
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Reported By:                schmidts
Assigned To:                
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Project:                    Asterisk
Issue ID:                   17400
Category:                   Channels/chan_sip/CodecHandling
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     feedback
Asterisk Version:           1.6.2.7 
JIRA:                       SWP-1579 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-05-26 04:05 CDT
Last Modified:              2010-06-03 12:19 CDT
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Summary:                    Writeformat Slin instead Alaw after attendend
Transfer when using Answer before Dial without Moh
Description: 
I´ve found a Problem when an attendend Transfer is done when the call to
the transfered has an answer before the dial. This only happens when no
Musiconhold is used when dialing and the Call is transfered after the
target of the refer answeres the call. We use Alaw on all phones, and
asterisk uses Slin for the Musiconhold also for the ringing signal before
the call gets answered.


If a call comes in to exten 123 and Phone A answers the Call, set the call
to Hold, then dials 456, wait for Phone B to answer the call and then refer
the call to Phone B the Write Format of the Call leg A stays on Slin. While
the Caller waits for the Attendend Transfer to be finished he hears the
default musiconhold in this case the macroform-cold_day.wav file and the
channel write format is slin, but after the transfer the write format
should go back to alaw. 

i can reproduce this on every call with this simple dialplan:

exten => 123,1,Dial(SIP/phoneA,120)

exten => 456,1,Answer
exten => 456,n,Dial(SIP/phoneB,120)


what i see in the debug is that the Call leg A is on write format slin
while hearing the moh and is set to alaw when moh stops, but then the
masquerade puts it in the structure of call leg C and then the write format
is changed to slin again even call leg C had write format alaw before.
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 (0122907) schmidts (reporter) - 2010-06-03 12:19
 https://issues.asterisk.org/view.php?id=17400#c122907 
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the symptom is bad sound quality for the caller who get transfered cause
the write code of this call leg is slin instead of alaw. The caller hears
mostly a ringing sound or even bad inteference of the opponent. The
opponent hears the caller without any quality problem.

a full debug (level 10) is allready attached. The problem which is see
starts at row 358 of the debug log. There the Moh is stopped and the
channel is set to write format alaw. This is the normal behavior i have
seen when the target of the attendend transfer has no answer before the
dial.

But on Row 375 of the debug log the write format is set to slin again. 

Issue History 
Date Modified    Username       Field                    Change               
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2010-06-03 12:19 schmidts       Note Added: 0122907                          
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