[asterisk-bugs] [Asterisk 0016793]: T38 flow states HDLC carrier immediately down when writing TSI to fax, but were up

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=16793 
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Reported By:                rlr2maverick
Assigned To:                
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Project:                    Asterisk
Issue ID:                   16793
Category:                   Applications/app_fax
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
Asterisk Version:           1.6.1.14 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): 1.6.1 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-02-09 09:10 CST
Last Modified:              2010-02-10 07:04 CST
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Summary:                    T38 flow states HDLC carrier immediately down when
writing TSI to fax, but were up
Description: 
Good morning,

our setup is based on asterisk 1.6.1.14 & spandsp 0.0.6-pre17. We're
always receiving fax with no error.

When sending we're experiencing a quite strange chan_sip codecs
negotiation, selecting ulaw (8kbit??? with fax @14400 ???) even if slin is
preferred and available.

At the first write (TSI) from asterisk to the channel remote side (fax)
we're encountering HDLC carrier down and the transmission never takes
place.

T38 nego can't proceed and fax is never sent.

Is there any experience to share ?

Indeed,
RLR
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 (0117940) rlr2maverick (reporter) - 2010-02-10 07:04
 https://issues.asterisk.org/view.php?id=16793#c117940 
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some further investigations lead us to te well known sequence

Got T.38 Re-invite without audio. Keeping RTP active during T.38 session.
SIP/2.0 488 Not acceptable here

by the way our dump stays under this common situation.

Our ATA model is audiocodes mp202 

Issue History 
Date Modified    Username       Field                    Change               
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2010-02-10 07:04 rlr2maverick   Note Added: 0117940                          
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