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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I am facing some problems with sending fax calls. I am using
G.711 codec. However, my service provider (Level-3) does not support T.38 fax
relay.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>According to Level-3 they “think” the problem
lies in the “Media Description” field of the SDP message I am
sending them. The problem is related to the “Media Format” sub-field
(value 101) that I am sending, which according to them should be removed.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The SDP “Media Description” field I am sending,
looks as follows:</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>“m=audio 20744 RTP/AVP 0 101” </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>which is decoded by Ethereal as follows:</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Media Type: audio</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Media</span></font><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Port</span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>: 20744</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=SV style='font-size:10.0pt;
font-family:Arial'>Media Proto: RTP/AVP</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=SV style='font-size:10.0pt;
font-family:Arial'>Media Format: ITU-T G.711 PCMU</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=SV style='font-size:10.0pt;
font-family:Arial'>Media Format: 101</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=SV style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>My call is initiated by Asterisk which is sent to Level-3
via SER</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Asterisk -</span></font><font size=2 face=Wingdings><span
style='font-size:10.0pt;font-family:Wingdings'>à</span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> SER -</span></font><font
size=2 face=Wingdings><span style='font-size:10.0pt;font-family:Wingdings'>à</span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> Level-3</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The SIP call flow looks fine for the call. The sending fax
sends the page and then gives an error. The receiving side gives me an error
and prints a blank page. </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>My questions are as follows:</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in'><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>1)<font size=1
face="Times New Roman"><span style='font:7.0pt "Times New Roman"'>
</span></font></span></font><font size=2 face=Arial><span style='font-size:
10.0pt;font-family:Arial'>Could the “Media Format” 101 be the
problem? If so, how do I remove the 101? This change is probably in Asterisk,
as it initiates the call, and not SER, or probably both.</span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in'><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>2)<font size=1
face="Times New Roman"><span style='font:7.0pt "Times New Roman"'>
</span></font></span></font><font size=2 face=Arial><span style='font-size:
10.0pt;font-family:Arial'>If not, should I be looking elsewhere in SER/Asterisk
to solve this problem?</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>regards,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>SCM</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
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