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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">The most likely cause is that there is something wrong in the format of the ACK which is causing the far end to not recognize it as being the ACK for that 4XX response. So the far end will
continue to retransmit the 4XX response. On the OpenSIPS side, these are recognized as retransmissions so the previous response is resent without triggering the failure route.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">The reason it happens on 4XX but not on 200 OK is that ACKs within a dialog – for 200 OK responses to INVITE or BYE – are actually requests themselves and are sent end-to-end just like
INVITEs and BYEs. These ACKs are constructed following the rules for any request within a dialog [1].<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">ACKs to failure responses, however, are transmitted at the transaction layer which means in this case they are being generated by OpenSIPS directly. Transactional ACKs are not requests
and the rules for constructing them are different [2]. The most important parts are that the Via and Request-URI headers must match those in the initial request exactly.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">I have encountered this problem several times when my manipulations of messages in the routing script cause the ACKs to be malformed. I would suggest capturing a SIP trace of the failing
transaction and verify the ACK is constructed properly.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">[1] <a href="https://tools.ietf.org/html/rfc3261#section-12.2.1.1">
https://tools.ietf.org/html/rfc3261#section-12.2.1.1</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri">[2] <a href="https://tools.ietf.org/html/rfc3261#section-17.1.1.3">
https://tools.ietf.org/html/rfc3261#section-17.1.1.3</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri;color:black">Ben Newlin</span><span style="font-size:11.0pt;font-family:Calibri"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Calibri"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-family:Calibri;color:black">From: </span>
</b><span style="font-family:Calibri;color:black"><users-bounces@lists.opensips.org> on behalf of Richard Robson <rrobson@greenlightcrm.com><br>
<b>Organization: </b>Greenlight Innovation<br>
<b>Reply-To: </b>OpenSIPS users mailling list <users@lists.opensips.org><br>
<b>Date: </b>Friday, October 7, 2016 at 12:46 PM<br>
<b>To: </b>OpenSIPS users mailling list <users@lists.opensips.org><br>
<b>Subject: </b>[OpenSIPS-Users] multiple retransmissions on 4XX after ACK<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">Hi Guys,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">Not sure if this a problem or normal behaviour or I'm doing something wrong.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">after a 4XX is sent and the ACK recieved I can see 3 retransmissions of
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">the 4XX message all with corresponding ACKs. Whywould it re transmit
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">after an ACK<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">in the logs in the reply route I only see one. Is there something I
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">should be doing or is this normal behaviour. It doesnt do it with BYEs<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">We are testing with BT next wee and I'd like everything to be shipshape<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">this is from the carrier to opensips<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│INVITE sip:<a href="mailto:441618501059@gl-sip-03.greenlightcrm.com">441618501059@gl-sip-03.greenlightcrm.com</a> SIP/2.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> PSTN CARRIER OPENSIPS <o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│Record-Route: <sip:109.239.96.133;lr;ftag=0UUHS0000030000E<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> ──────────┬─────────
<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">──────────┬─────────│01001u1J9XWPK0DDUY6X;did=e7f.7bf9fe87><o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> │ INVITE (SDP) │ │Via: SIP/2.0/UDP
<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">109.239.96.133:5060;branch=z9hG4bK547c.48<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:38.425641 │ ──────────────────────────> │ │a4d4.0<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.004634 │ 100 Giving a try │ │Via: SIP/2.0/UDP
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">194.145.191.131:5060;branch=z9hG4bK00E0F5<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:38.430275 │ <────────────────────────── │
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│0E45333EAEE2FDC3E18D<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.105251 │ 180 Ringing │ │From:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><sip:<a href="mailto:01382250029@194.145.191.131">01382250029@194.145.191.131</a>>;tag=0UUHS000003000<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:38.535526 │ <────────────────────────── │
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│1D01001u1J9XWPK0DDUY6X<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.128720 │ 180 Ringing │ │To:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><sip:<a href="mailto:441618501059@109.239.96.133">441618501059@109.239.96.133</a>><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:38.664246 │ <<<──────────────────────── │ │Call-ID:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">4515e0000ef5-57f7d085-4d7d4603-f256d18-48e7f14@12<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +10.118555 │ 408 Request Timeout │ │0.0.1<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:48.782801 │ <────────────────────────── │ │CSeq:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">33717 INVITE<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.000610 │ ACK │ │Contact:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><sip:194.145.191.131:5060><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:48.783411 │ ──────────────────────────> │
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│Allow-Events: refer<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.436750 │ 408 Request Timeout │ │Allow: INVITE,
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">ACK, BYE, CANCEL, OPTIONS, PRACK, INFO, REF<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:49.220161 │ <<<──────────────────────── │ │, NOTIFY,
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">SUBSCRIBE, UPDATE<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.000636 │ ACK │ │Content-Type:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">application/sdp<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:49.220797 │ ────────────────────────>>> │
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│Max-Forwards: 69<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +1.003961 │ 408 Request Timeout │ │Supported:
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">timer, replaces, histinfo, 100rel<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:50.224758 │ <<<──────────────────────── │
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">│User-Agent: TELES-SBC<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.000705 │ ACK │ │Content-Length: 463<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:50.225463 │ ────────────────────────>>> │ │<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +2.005938 │ 408 Request Timeout │ │v=0<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:52.231401 │ <<<──────────────────────── │ │o=-
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">1890151066 0 IN IP4 194.145.191.134<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> +0.000651 │ ACK │ │s=TELES-SBC<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> 17:42:52.232052 │ ────────────────────────>>> │ │c=IN IP4
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">194.145.191.134<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> │ │ │t=0 0<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"> │<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">Regards,<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">--
<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">Richard Robson<o:p></o:p></span></p>
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<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">Greenlight Support<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">01382 843843<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><a href="mailto:support@greenlightcrm.com">support@greenlightcrm.com</a><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">_______________________________________________<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black">Users mailing list<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><a href="mailto:Users@lists.opensips.org">Users@lists.opensips.org</a><o:p></o:p></span></p>
</div>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><a href="http://lists.opensips.org/cgi-bin/mailman/listinfo/users">http://lists.opensips.org/cgi-bin/mailman/listinfo/users</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas;color:black"><o:p> </o:p></span></p>
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