[asterisk-bugs] [Asterisk 0016756]: app_fax doesn't receive fax with T.38

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=16756 
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Reported By:                viniciusfontes
Assigned To:                
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Project:                    Asterisk
Issue ID:                   16756
Category:                   Applications/app_fax
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     feedback
Asterisk Version:           SVN 
JIRA:                       SWP-845 
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:             2010-02-02 13:56 CST
Last Modified:              2010-02-05 05:18 CST
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Summary:                    app_fax doesn't receive fax with T.38
Description: 
When I try to receive a fax from a provider that supports T.38 using
ReceiveFAX() provided by app_fax.so, the fax transmission ends prematurely
with an error.

What happens (according to Kevin Fleming) is this:

"In this call, Asterisk sent a re-INVITE to T.38 mode
from audio mode, the provider accepted it, and then Asterisk
acknowledged it. Immediately afterwards, Asterisk sent a re-INVITE
*back* to audio mode, which the provider accepted (and included T.38
capabilities in their response). Because of this, the FAX reception
process failed since the T.38 session was destroyed."

For reference, here is a link to the original mailing list thread: 
http://lists.digium.com/pipermail/asterisk-users/2010-February/244136.html
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 (0117774) viniciusfontes (reporter) - 2010-02-05 05:18
 https://issues.asterisk.org/view.php?id=16756#c117774 
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Good to know! I always tought the config on sip.conf would make the SDP
negotiation use those values.

I got a full debug on app_fax and it seems to me that the transmission
starts at 9600bps as expected but for some reason it falls back to 7200bps,
4800bps and finally to 2400bps where the transmission finally occurs.

Posted the log as app_fax_debug.txt.gz 

Issue History 
Date Modified    Username       Field                    Change               
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2010-02-05 05:18 viniciusfontes Note Added: 0117774                          
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