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    <font face="monospace">Hi Ali,<br>
      <br>
      The ACK is routed to the Contact address in 200 OK. So that
      Contact you set does not point back to your server - and probably
      MST is sending the ACK to some other destination.<br>
      <br>
      Regards,<br>
    </font>
    <pre class="moz-signature" cols="72">Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
  <a class="moz-txt-link-freetext" href="https://www.opensips-solutions.com">https://www.opensips-solutions.com</a>
  <a class="moz-txt-link-freetext" href="https://www.siphub.com">https://www.siphub.com</a></pre>
    <div class="moz-cite-prefix">On 08.04.2025 18:03, Ali Dogan wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CWLP265MB406238891EDDEAC041A7896BA1B52@CWLP265MB4062.GBRP265.PROD.OUTLOOK.COM">
      <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
      <style type="text/css" style="display:none;">P {margin-top:0;margin-bottom:0;}</style>
      <span
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Hello
        All,<br>
        <br>
        I'm trying to integrate OpenSIP with MS Teams. I'm using
        opensips with Topology Hiding module. Therefore, I'm adding FQDN
        to Contact and but MS Teams still not sending ACK to my 200 OK
        Shown in below. <br>
        <br>
        Is there anything wrong with my 200Ok I send?<br>
        <br>
        SIP/2.0 200 OK</span>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        VIA:  SIP/2.0/TLS 52.114.76.76:5061;branch=z9hG4bKd29ef91c</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Record-Route:
         <a class="moz-txt-link-rfc2396E" href="sip:sip-du-a-eu.pstnhub.microsoft.com:5061;transport=tls;lr"><sip:sip-du-a-eu.pstnhub.microsoft.com:5061;transport=tls;lr></a></div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        From:  "Ali Dogan"
<<a class="moz-txt-link-freetext" href="sip:+">sip:+</a><CALLING_PARTY>@sip.pstnhub.microsoft.com:5061;user=phone>;tag=90feae90c00c4745b162d0a69fd532bc</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        To:
 <<a class="moz-txt-link-freetext" href="sip:+">sip:+</a><Called_Party>@<MY_DOMAIN>:5061;user=phone>;tag=r4FmDXjKF7amm</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Call-ID: 778bfb54c5505df2b350f7c8ac8a6832</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        CSeq:  1 INVITE</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Contact:
 <<a class="moz-txt-link-freetext" href="sip:+">sip:+</a><Called_Party>@<MY_DOMAIN>:5061;transport=tls;did=98f.cbe7a852></div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Accept:  application/sdp</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Allow:  INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO,
        UPDATE, REGISTER, REFER, NOTIFY</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Require:  timer</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Supported:  timer, path, replaces</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Allow-Events:  talk, hold, conference, refer</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Session-Expires:  3600;refresher=uac</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Content-Type:  application/sdp</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Content-Disposition:  session</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Content-Length:  510</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        X-Warning:  CLI Should be in E164 Format</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Remote-Party-ID:  "Called_PARTY"
<<a class="moz-txt-link-freetext" href="sip:Called_PARTY@">sip:Called_PARTY@</a><MY_DOMAIN>>;party=calling;privacy=off;screen=no</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        <br>
        <br>
        Best Regards,</div>
      <div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
        Ali</div>
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style="width:100%;direction:ltr;border-collapse:collapse;font-size:1px;"
          cellspacing="0" cellpadding="0" border="0">
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                  cellspacing="0" cellpadding="0" border="0">
                  <tbody>
                    <tr style="font-size:0;">
                      <td style="padding:30px 0 0;vertical-align:top;"
                        align="left">
                        <table
style="width:500px;border-collapse:collapse;font-size:0;"
                          cellspacing="0" cellpadding="0" border="0">
                          <tbody>
                            <tr style="font-size:0;">
                              <td
style="padding:0 0 20px;border-top:none;border-right:none;border-bottom:solid 1px #B1BAD4;border-left:none;vertical-align:top;"
                                align="left">
                                <table
style="border-collapse:collapse;font-size:0;" cellspacing="0"
                                  cellpadding="0" border="0">
                                  <tbody>
                                    <tr style="font-size:0;">
                                      <td
style="padding:0 20px 0 0;border-top:none;border-right:solid 1px #CCCCCC;border-bottom:none;border-left:none;vertical-align:middle;"
                                        align="left">
                                        <table
style="border-collapse:collapse;font-size:0;font-style:normal;font-weight:700;line-height:normal;white-space:nowrap;"
                                          cellspacing="0"
                                          cellpadding="0" border="0">
                                          <tbody>
                                            <tr style="font-size:14px;">
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style="padding:0;vertical-align:top;font-family:Verdana;" align="left">
                                                <p
style="color:#041729;margin-top:0px;margin-bottom:0px;">Ali Dogan<span
style="font-family:remialcxesans;font-size:1px;color:#FFFFFF;line-height:1px;">​<span
style="font-family:'template-IIW3pcg7EeunrQANOhMDEQ';">​</span><span
style="font-family:'zone-1';">​</span><span
style="font-family:'zones-AQ';">​</span></span></p>
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                                              <td
style="padding:15px 0 0;vertical-align:top;" align="left">
                                                <p
style="margin-top:0px;margin-bottom:0px;"><a href="http://www.plan.com/"
                                                    target="_blank"
                                                    id="LPlnk689713"
style="text-decoration:none;" moz-do-not-send="true"><img
src="http://www.plan.com/signatures/v2/plan-logo.png" title="plan.com"
                                                      alt="plan.com"
style="width:157px;min-width:157px;max-width:157px;font-size:12px;"
moz-do-not-send="true" width="157" border="0"></a></p>
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style="padding:0 20px;border-top:none;border-right:solid 1px #B1BAD4;border-bottom:none;border-left:none;vertical-align:middle;"
                                        align="left">
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style="border-collapse:collapse;font-size:0;font-style:normal;font-weight:400;white-space:nowrap;"
                                          cellspacing="0"
                                          cellpadding="0" border="0">
                                          <tbody>
                                            <tr style="font-size:12px;">
                                              <td
style="padding:0;vertical-align:top;font-family:Verdana;" align="left">
                                                <p
style="color:#041729;margin-top:0px;margin-bottom:0px;"><a
href="tel:+44(0)3300%2088%2018%2018" target="_blank" id="LPlnk689713"
style="text-decoration:none;color:#041729;" moz-do-not-send="true">+44(0)3300 88 18 18</a></p>
                                              </td>
                                            </tr>
                                            <tr
style="font-size:12px;font-weight:700;">
                                              <td
style="padding:8px 0 0;vertical-align:top;font-family:Verdana;"
                                                align="left">
                                                <p
style="color:#000001;margin-top:0px;margin-bottom:0px;"><a
href="mailto:alidogan@plan.com" target="_blank" id="LPlnk689713"
style="text-decoration:none;color:#041729;" moz-do-not-send="true"
class="moz-txt-link-freetext">alidogan@plan.com</a></p>
                                              </td>
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style="padding:8px 0 0;vertical-align:top;" align="left">
                                                <table
style="border-collapse:collapse;font-size:0;line-height:normal;"
                                                  cellspacing="0"
                                                  cellpadding="0"
                                                  border="0">
                                                  <tbody>
                                                    <tr
style="font-size:0;">
                                                      <td
style="padding:0 7px 0 0;vertical-align:middle;" align="center">
                                                        <p
style="margin-top:0px;margin-bottom:0px;"><a
href="https://www.facebook.com/plan.im" target="_blank" id="LPlnk689713"
style="text-decoration:none;" moz-do-not-send="true"><img
src="http://www.plan.com/signatures/v3/facebook.png" title="Facebook"
                                                          alt="Facebook"
style="width:20px;min-width:20px;max-width:20px;font-size:12px;"
moz-do-not-send="true" width="20" border="0"></a></p>
                                                      </td>
                                                      <td
style="padding:0 7px;vertical-align:middle;" align="center">
                                                        <p
style="margin-top:0px;margin-bottom:0px;"><a
href="https://www.instagram.com/plandotcom" target="_blank"
id="LPlnk689713" style="text-decoration:none;" moz-do-not-send="true"><img
src="http://www.plan.com/signatures/v3/instagram.png" title="Instagram"
alt="Instagram"
style="width:20px;min-width:20px;max-width:20px;font-size:12px;"
moz-do-not-send="true" width="20" border="0"></a></p>
                                                      </td>
                                                      <td
style="padding:0 7px;vertical-align:middle;" align="center">
                                                        <p
style="margin-top:0px;margin-bottom:0px;"><a
href="https://www.linkedin.com/company/plan-com" target="_blank"
id="LPlnk689713" style="text-decoration:none;" moz-do-not-send="true"><img
src="http://www.plan.com/signatures/v3/linkedin.png" title="LinkedIn"
                                                          alt="LinkedIn"
style="width:20px;min-width:20px;max-width:20px;font-size:12px;"
moz-do-not-send="true" width="20" border="0"></a></p>
                                                      </td>
                                                      <td
style="padding:0 0 0 7px;"> </td>
                                                    </tr>
                                                  </tbody>
                                                </table>
                                              </td>
                                            </tr>
                                          </tbody>
                                        </table>
                                      </td>
                                      <td
style="padding:0 20px;vertical-align:middle;line-height:normal;"
                                        align="left">
                                        <p
style="margin-top:0px;margin-bottom:0px;"><img
src="http://www.plan.com/signatures/v4/2024-awards-logos.png" alt=""
style="width:615px;min-width:615px;max-width:615px;font-size:0;"
                                            moz-do-not-send="true"
                                            width="615" border="0"></p>
                                      </td>
                                    </tr>
                                  </tbody>
                                </table>
                              </td>
                            </tr>
                            <tr style="font-size:0;">
                              <td style="padding:0;vertical-align:top;"
                                align="left">
                                <table
style="width:100%;border-collapse:collapse;font-size:0;" cellspacing="0"
                                  cellpadding="0" border="0">
                                  <tbody>
                                    <tr style="font-size:0;">
                                      <td style="vertical-align:top;"
                                        align="left">
                                        <table
style="border-collapse:collapse;font-size:0;font-style:normal;font-weight:400;white-space:normal;"
                                          cellspacing="0"
                                          cellpadding="0" border="0">
                                          <tbody>
                                            <tr
                                              style="font-size:9.33px;">
                                              <td
style="padding:20px 0;vertical-align:top;font-family:Verdana;"
                                                align="left">
                                                <p
style="color:#AFB3C2;margin-top:0px;margin-bottom:0px;"><a
href="http://www.plan.com/" target="_blank" id="LPlnk689713"
title="http://www.plan.com/" style="text-decoration:none;color:#AFB3C2;"
moz-do-not-send="true">plan.com</a> is the trading name of Plan
                                                  Communications
                                                  Limited, registered in
                                                  the Isle of Man with
                                                  company number 010273V
                                                  and Registered Office
                                                  at No.5 Victoria
                                                  Street, Douglas, Isle
                                                  of Man, IM1 2LR. This
                                                  email and any
                                                  attachments to it may
                                                  be confidential and
                                                  are intended solely
                                                  for the use of the
                                                  individual to whom it
                                                  is addressed. Any
                                                  views or opinions
                                                  expressed are solely
                                                  those of the author
                                                  and do not necessarily
                                                  represent those of
                                                  Plan. If you are not
                                                  the intended recipient
                                                  of this email, you
                                                  must neither take any
                                                  action based upon its
                                                  contents, nor copy or
                                                  show it to anyone.
                                                  Please contact the
                                                  sender if you believe
                                                  you have received this
                                                  email in error.<br>
                                                </p>
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      <br>
      <fieldset class="moz-mime-attachment-header"></fieldset>
      <pre class="moz-quote-pre" wrap="">_______________________________________________
Users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Users@lists.opensips.org">Users@lists.opensips.org</a>
<a class="moz-txt-link-freetext" href="http://lists.opensips.org/cgi-bin/mailman/listinfo/users">http://lists.opensips.org/cgi-bin/mailman/listinfo/users</a>
</pre>
    </blockquote>
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