[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:                     feedback
Asterisk Version:           1.6.1.14 
JIRA:                       SWP-890 
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:              2010-02-12 03:34 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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 (0118026) rlr2maverick (reporter) - 2010-02-12 03:34
 https://issues.asterisk.org/view.php?id=16793#c118026 
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good morning there

no chance to send fax altering in chan_sip.c from 

19397 --------------> p->t38id = ast_sched_add(sched, 5000, sip_t38_abort,
dialog_ref(p, "passing dialog ptr into sched structure based on t38id for
sip_t38_abort."));

to

19397 --------------> p->t38id = ast_sched_add(sched, 185000,
sip_t38_abort, dialog_ref(p, "passing dialog ptr into sched structure based
on t38id for sip_t38_abort."));

waiting for the fax data to flow, while p->t38.state == T38_PEER_REINVITE
only null frame format 5/0 len 0 goes from asterisk to the fax. 

I'm not sure the reinvite reply to 'SIP/2.0 100 Trying' has to come
directly from ATA/Fax or, missing it I would promote T.38 state from
T38_PEER_REINVITE to T38_ENABLED waiting for eventual further errors from
the peer if any. 

Issue History 
Date Modified    Username       Field                    Change               
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2010-02-12 03:34 rlr2maverick   Note Added: 0118026                          
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