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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Hi,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Sorry, the RFC says that a= is not mandatory, m= is enough. <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I was just confused why FS in some scenario puts it and in other doesn’t, despite using only G711@8000.</span><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-right:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Alex Massover <br><b>Sent:</b> <span lang=HE dir=RTL>יום</span><span dir=LTR></span><span dir=LTR></span> <span lang=HE dir=RTL>ה</span><span dir=LTR></span><span dir=LTR></span> 25 <span lang=HE dir=RTL>אוגוסט</span><span dir=LTR></span><span dir=LTR></span> 2011 12:26<br><b>To:</b> 'freeswitch-users@lists.freeswitch.org'<br><b>Subject:</b> Forcing CN offer<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hello,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m working on the following scenarios:<o:p></o:p></p><p class=MsoNormal>scenario 1: A <span style='font-family:Wingdings'>à</span> FS <span style='font-family:Wingdings'>à</span> B<o:p></o:p></p><p class=MsoNormal>scenario 2: C <span style='font-family:Wingdings'>à</span> FS <span style='font-family:Wingdings'>à</span> A<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Where A supports CN (a=rtpmap:13 CN/8000) and requires CN negotiation, and B and C do not support and aren’t able to negotiate it.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I successfully implemented scenario 1, CN is negotiated between A party and FS, and not negotiated between FS and B.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>But scenario 2 doesn’t work for me! When C doesn’t offer CN in INVITE towards FS, FS also doesn’t offer CN in SDP in INVITE towards A. <o:p></o:p></p><p class=MsoNormal>And nothing helps, tried all the combination of VAD options. Gateway A is in the same internal sip profile in both scenarios.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This is the SDP in INVITE from C to FS:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal> Media Description, name and address (m): audio 30224 RTP/AVP 0 8 18 101<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): rtpmap:0 PCMU/8000<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): rtpmap:8 PCMA/8000<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): rtpmap:18 G729/8000<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): fmtp:18 annexb=no<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): rtpmap:101 telephone-event/8000<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): fmtp:101 0-16<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): silenceSupp:off - - - -<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): ptime:20<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): sendrecv<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>And this is the SDP from FS towards A:<o:p></o:p></p><p class=MsoNormal> Media Description, name and address (m): audio 23564 RTP/AVP 0 8 101 13<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): rtpmap:101 telephone-event/8000<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): fmtp:101 0-16<o:p></o:p></p><p class=MsoNormal> Media Attribute (a): ptime:20<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>FS even puts 13 in m= attribute, but doesn’t add a= attribute for rtpmap:13.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Is that a bug?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>--<o:p></o:p></p><p class=MsoNormal>Best Regards<o:p></o:p></p><p class=MsoNormal>Alex Massover.<o:p></o:p></p></div></div><br><br>
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