[asterisk-bugs] [Asterisk 0015578]: SendFAX not working with T.38

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
====================================================================== 
https://issues.asterisk.org/view.php?id=15578 
====================================================================== 
Reported By:                ChrisDE
Assigned To:                
====================================================================== 
Project:                    Asterisk
Issue ID:                   15578
Category:                   Applications/app_fax
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
Asterisk Version:           1.6.0.11-rc1 
Regression:                 No 
SVN Branch (only for SVN checkouts, not tarball releases): 1.6.0 
SVN Revision (number only!): 208502 
Request Review:              
====================================================================== 
Date Submitted:             2009-07-24 12:51 CDT
Last Modified:              2009-07-27 11:15 CDT
====================================================================== 
Summary:                    SendFAX not working with T.38
Description: 
After several trials with SendFAX and several fax machines it gives me the
impression that it does not work at all.
With one fax e.g. I get the info

[Jul 24 15:36:38] WARNING[11293]: app_fax.c:178 phase_e_handler: Error
transmitting fax. result=48: Disconnected after permitted retries.
[Jul 24 15:36:38] WARNING[11293]: app_fax.c:680 transmit: Transmission
failed

after exchanging some UDPTL packets.
Another fax machine results in

[Jul 24 15:15:55] WARNING[11184]: app_fax.c:128 span_message: WARNING T.30
t30_non_ecm_get_chunk in bad state 3
...
[Jul 24 15:15:57] WARNING[11184]: app_fax.c:178 phase_e_handler: Error
transmitting fax. result=13: Unexpected message received.
[Jul 24 15:15:57] WARNING[11184]: app_fax.c:680 transmit: Transmission
failed

this is always the same with this fax machine not only sometimes

with another fax machine there seems not to be t.38 at all. after
connecting with g711 it only sais

stars24*CLI>
<--- SIP read from UDP://213.148.136.2:5060 --->
hello
<------------->

several times and then it tells

[Jul 24 15:13:43] WARNING[11081]: app_fax.c:178 phase_e_handler: Error
transmitting fax. result=49: The call dropped prematurely.
[Jul 24 15:13:43] WARNING[11081]: app_fax.c:677 transmit: Transmission
error

always. Not only one time out of 10. I also have to say that all of the
calls are terminated with German QSC who support T.38. And the reportet
results are just different fax machines that where called with the same sip
account at QSC.

====================================================================== 

---------------------------------------------------------------------- 
 (0108257) kpfleming (administrator) - 2009-07-27 11:15
 https://issues.asterisk.org/view.php?id=15578#c108257 
---------------------------------------------------------------------- 
I don't see how this is a problem with Asterisk's T.38 support or with
app_fax at all. In both call4 and call6, the Huawei switch sent a reinvite
requesting that we switch to T.38, and Asterisk responded with '200 OK'
with a proper T.38 answer that matches the offer in the INVITE. However,
the Huawei switch never ACKs the '200 OK', and eventually Asterisk times
out and hangs up the call because that ACK is critical for proper SIP
transaction handling.

I'm going to close this issue; if you can determine that something
Asterisk is doing is the reason *why* the Huawei switch is not ACKing the
response, feel free to open an issue against chan_sip with the required
information. 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2009-07-27 11:15 kpfleming      Note Added: 0108257                          
======================================================================