[asterisk-bugs] [Asterisk 0014849]: [patch] SendFax function not working as expected on > 1.6.0.7

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
====================================================================== 
https://issues.asterisk.org/view.php?id=14849 
====================================================================== 
Reported By:                afosorio
Assigned To:                
====================================================================== 
Project:                    Asterisk
Issue ID:                   14849
Category:                   Channels/chan_sip/T.38
Reproducibility:            always
Severity:                   block
Priority:                   normal
Status:                     ready for review
Target Version:             1.6.0.11
Asterisk Version:           1.6.0.7 
Regression:                 Yes 
SVN Branch (only for SVN checkouts, not tarball releases): 1.6.0 
SVN Revision (number only!):  
Request Review:              
====================================================================== 
Date Submitted:             2009-04-07 15:51 CDT
Last Modified:              2009-06-15 17:36 CDT
====================================================================== 
Summary:                    [patch] SendFax function not working as expected on
> 1.6.0.7
Description: 
When trying to send a fax via callfile using T.38 in asterisk version
1.6.0.5 it works fine, but after upgrading to asterisk 1.6.0.7 or newer it
does not work. When receiving re-INVITE from media gateway (Cisco AS-5400)
Asterisk ends call answering 488 Not acceptable here. I am running Asterisk
under Debian kernel 2.6.18-6-686. I am attaching captures both for scenario
which works and scenario which does not work. 
====================================================================== 

---------------------------------------------------------------------- 
 (0106434) dimas (reporter) - 2009-06-15 17:36
 https://issues.asterisk.org/view.php?id=14849#c106434 
---------------------------------------------------------------------- 
Sure.
chan_sip used to instantly accept T38 reinvite offer when offered by
remote peer. After accepting the offer, chan_sip sends AST_T38_NEGOTIATED.
app_fax receives the frame and knows that switchover is done, terminates
audio loop and switches to T38 mode.

In the commit 183108 ( see http://reviewboard.digium.com/r/200/ ) file
changed the logic of chan_sip to not blindly accept T38 reinvite but send
AST_T38_REQUEST_NEGOTIATE request frame into asterisk core. So if someone
(like application) is interested in the T38, it will agree to switch (by
indicating AST_T38_REQUEST_NEGOTIATE back) and then chan_sip will finally
do the switchover (again, producing AST_T38_NEGOTIATED at the end). If
noone on the application side agrees to T38 in 5 seconds, chan_sip will
refuse the offer with 488 Not Acceptable Here.

The only problem is that app_fix was not updated to account that change so
it keeps waiting for AST_T38_NEGOTIATED which will never come until the
application itself confirms AST_T38_REQUEST_NEGOTIATE coming from the
channel driver. 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2009-06-15 17:36 dimas          Note Added: 0106434                          
======================================================================