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<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'>Faxing over T.38 from experience has certainly been a better
experience than over G711u bypass. Of course there are some implementations of
T.38 that interoperate with each other better than others. My experience with
AudioCodes, Linksys/Sipura, and Grandstream has been very positive.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'>One of the common potential problems with either approach is
the behaviour of the signaling in response to which end (caller, callee, or
both) of the session is responsible for initiating the re-INVITE for T.38. When
supporting wholesale customers it is not always possible to configure the
behaviour of the ATAs/IADs and the only way to ensure fax will at least always
be “detected” is to have one of endpoint gateways/ATAs/IADs detect
fax as the caller and the callee. The next fun piece to tackle once that’s
configured is to ensure that all endpoints properly support handling SIP 491
Request Pending response codes to avoid a race condition which can cause INVITE
“glare” if one endpoint is configured to detect faxes and re-INVITE
for both caller and callee and the other is set to detect faxes and re-INVITE on
either.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'>Justin<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Calibri><span style='font-size:
10.0pt;color:blue'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
voiceops-bounces@voiceops.org [mailto:voiceops-bounces@voiceops.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Ujjval Karihaloo<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, January 06, 2010
7:01 PM<br>
<b><span style='font-weight:bold'>To:</span></b> voiceops@voiceops.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [VoiceOps] VoIP T38 Fax
reliability</span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>I
know this a thorn in everyones flesh, I would like to know of experiences with
T38 Voip Faxing. We have had good and bad. Those that don’t work just
don’t and they don’t even want to troubleshoot and just switch over
to an Analog line for Fax. We mostly use AudioCodes and Sipura T38 ATAs.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>Any
of you folks do T38 and whats the experience like.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
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