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<p class="MsoNormal" style="background:white"><span style="color:#212121">Hi,<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="color:#212121"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="color:#212121">We have a scenario where inbound calls from an upstream provider (chan_sip) sent downstream (chan_iax2) negotiates only g729
</span><span style="color:black">yet</span><span style="color:#212121"> RTP media contains g711</span><span style="color:black">.
</span><span style="color:#212121">Both the upstream and downstream trunks are limited to only offering g729 whilst the initial invite from our upstream provider offers both g711 and g729. Asterisk presumably simply forwards the media from iax2 trunk encapsulation
to sip encapsulation. Most calls surprisingly work, presumably by the caller's system identifying the incoming media as g711</span><span style="color:black">,</span><span style="color:#212121"> whilst very few callers don't hear the IVR prompt.</span><span style="color:black">
</span><span style="color:#212121">The downstream is unfortunately not within our control but can't be anything other than Asterisk, considering it's using iax2 in trunk mode.<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><o:p> </o:p></p>
<p class="MsoNormal" style="background:white"><span style="color:black">We are running Asterisk 16.13.0, not sure what version the downstream is using.</span><o:p></o:p></p>
<p class="MsoNormal" style="background:white"><o:p> </o:p></p>
<p class="MsoNormal" style="background:white"><span style="color:#212121">caller -> upstream -> us -> downstream (IVR)<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><o:p> </o:p></p>
<p class="MsoNormal" style="background:white"><span style="color:black">Herewith the SIP portion of the call, between upstream and us:</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt;background:white"><span style="color:black"><img width="1261" height="742" style="width:13.1354in;height:7.7291in" id="Picture_x0020_1" src="cid:image002.jpg@01D690AC.C02E4200"></span><o:p></o:p></p>
<p class="MsoNormal" style="background:white"><span style="color:#212121"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="color:#212121"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="color:#212121">Wireshark unfortunately still cannot dissect iax2 trunk captures though, so I didn't know how to conclusively
</span><span style="color:black">identify where this problem </span><span style="color:#212121">originates.</span><span style="color:black"> I do however have a concern that the media we are receiving’s packet size indicates that it is most likely G729.</span><span style="color:#212121"><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Herewith the IAX2 trunk portion of the call, between us and downstream:<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"><img width="1210" height="709" style="width:12.6041in;height:7.3854in" id="Picture_x0020_2" src="cid:image004.jpg@01D690AC.C02E4200"><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Regards<br>
David Herselman<o:p></o:p></p>
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