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    <p>Hello,</p>
    <p>you have to provide the PCAP (or ngrep output) for such a call
      taken on kamailio system to see the headers of each sip message
      and try to understand where the issue is.</p>
    <p>Cheers,<br>
      Daniel<br>
    </p>
    <div class="moz-cite-prefix">On 18.05.20 09:38, Rex Lin (林昱頡) wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:HK2PR04MB3732C647C86DE6951A29E9C582B80@HK2PR04MB3732.apcprd04.prod.outlook.com">
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          <div><font size="2" face="Arial" color="#2F5496"><span
                style="font-size:10.5pt;">Hi,</span></font></div>
          <div><font size="2" face="Arial" color="#2F5496"><span
                style="font-size:10.5pt;"> </span></font></div>
          <div><font size="2" face="Arial" color="#2F5496"><span
                style="font-size:10.5pt;">Do you need further
                information? Actually, I am not sure if the process is
                normal, there‘s no problem with the call at least.</span></font></div>
          <div><font size="2" face="Arial" color="#2F5496"><span
                style="font-size:10.5pt;">Could it be caused any problem
                if all clients do fix_nated_register?</span></font></div>
          <div><font size="3" color="#2F5496"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" color="#1F497D"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="2" face="Arial" color="#1F497D"><span
                style="font-size:10.5pt;">Best Regards,</span></font></div>
          <div><font size="2" face="Arial" color="#1F497D"><span
                style="font-size:10.5pt;">Rex </span></font></div>
          <div><font size="3" color="#2F5496"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="2" face="Calibri"><span
                style="font-size:11pt;"><b>From:</b> Rex Lin (<font
                  face="新細明體">林昱頡</font>)
                <br>
                <b>Sent:</b> Friday, May 15, 2020 2:37 PM<br>
                <b>To:</b> Kamailio (SER) - Users Mailing List
                <a class="moz-txt-link-rfc2396E" href="mailto:sr-users@lists.kamailio.org"><sr-users@lists.kamailio.org></a><br>
                <b>Subject:</b> Re: [SR-Users] Issue of calls drop 32s</span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Hi Alex,</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Thanks for your reply.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">ICE/STUN haven’t been activated
                by our clients. All transmission traffic pass through a
                proxy server. Below is the screenshot of a normal call
                process.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3"><span style="font-size:12pt;"><img
                  src="cid:part2.DF12B831.ABF43F03@gmail.com" class=""><font
                  face="Calibri"> </font></span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Best Regards,</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Rex</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">-----Original Message-----<br>
                From: sr-users <<a
                  href="mailto:sr-users-bounces@lists.kamailio.org"
                  moz-do-not-send="true"><font color="#0563C1"><u>sr-users-bounces@lists.kamailio.org</u></font></a>>
                On Behalf Of Alex Balashov<br>
                Sent: Thursday, May 14, 2020 12:18 AM<br>
                To: Kamailio (SER) - Users Mailing List <<a
                  href="mailto:sr-users@lists.kamailio.org"
                  moz-do-not-send="true"><font color="#0563C1"><u>sr-users@lists.kamailio.org</u></font></a>><br>
                Subject: Re: [SR-Users] Issue of calls drop 32s</span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">It's a tell-tale sign of an
                end-to-end ACK from the caller not being forwarded
                properly to the callee. The server should not be
                forwarding such an ACK "to itself"; this suggests that
                its Request
                URI may be improperly constructed (it should be
                equivalent to the remote Contact URI of the callee in
                the 200 OK message), or that its Route headers are
                somehow incorrect (they should mirror the Record-Route
                set in the 200 OK).</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">-- Alex</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">On Wed, May 13, 2020 at
                04:07:16PM +0000, Rex Lin (<font face="新細明體">林昱頡</font>)
                wrote:</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> Hi,</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> It<font face="Courier New">’</font>s
                weird that the calls always drop after 32s while the
                callee is using public ip. Also, Server forwards ACK to
                itself with UDP, instead of forwarding to callee
                with TLS.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> Moreover, I cannot see <font
                  face="Courier New">“</font>Received<font face="Courier
                  New">”</font> in AOR as the callee finish the
                registration.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> I recognized it<font
                  face="Courier New">’</font>s marked by nat_uac_test(<font
                  face="Courier New">“</font>19<font face="Courier New">”</font>)
                and set with fix_nated_register(), the problem
                can be resolved.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> My scenario is as below,
                for your reference.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> 1.Kamailio version is
                4.4.7, listening public ip.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> 2.Caller it<font
                  face="Courier New">’</font>s behind NAT.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> 3.Clients of Linphone.</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> Do you know the reason why
                it happened?</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> Best Regards,</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> Rex</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">>
                _______________________________________________</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> Kamailio (SER) - Users
                Mailing List</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> <a
                  href="mailto:sr-users@lists.kamailio.org"
                  moz-do-not-send="true">sr-users@lists.kamailio.org</a></span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">> <a
                  href="https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users"
                  moz-do-not-send="true">https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users</a></span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">--</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Alex Balashov | Principal |
                Evariste Systems LLC</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Tel: +1-706-510-6800 /
                +1-800-250-5920 (toll-free)</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Web: <a
                  href="http://www.evaristesys.com/"
                  moz-do-not-send="true">http://www.evaristesys.com/</a>,
                <a href="http://www.csrpswitch.com/"
                  moz-do-not-send="true">http://www.csrpswitch.com/</a></span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">_______________________________________________</span></font></div>
          <div><font size="3" face="Calibri"><span
                style="font-size:12pt;">Kamailio (SER) - Users Mailing
                List</span></font></div>
          <div><font size="3"><span style="font-size:12pt;"><a
                  href="mailto:sr-users@lists.kamailio.org"
                  moz-do-not-send="true"><font face="Calibri">sr-users@lists.kamailio.org</font></a></span></font></div>
          <div><font size="3"><span style="font-size:12pt;"><a
                  href="https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users"
                  moz-do-not-send="true"><font face="Calibri">https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users</font></a></span></font></div>
          <div><font size="3"><span style="font-size:12pt;"> </span></font></div>
        </span></font>
      <br>
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      <pre class="moz-quote-pre" wrap="">_______________________________________________
Kamailio (SER) - Users Mailing List
<a class="moz-txt-link-abbreviated" href="mailto:sr-users@lists.kamailio.org">sr-users@lists.kamailio.org</a>
<a class="moz-txt-link-freetext" href="https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users">https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users</a>
</pre>
    </blockquote>
    <pre class="moz-signature" cols="72">-- 
Daniel-Constantin Mierla -- <a class="moz-txt-link-abbreviated" href="http://www.asipto.com">www.asipto.com</a>
<a class="moz-txt-link-abbreviated" href="http://www.twitter.com/miconda">www.twitter.com/miconda</a> -- <a class="moz-txt-link-abbreviated" href="http://www.linkedin.com/in/miconda">www.linkedin.com/in/miconda</a>
Funding: <a class="moz-txt-link-freetext" href="https://www.paypal.me/dcmierla">https://www.paypal.me/dcmierla</a></pre>
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