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    <p>Ovidiu <br>
    </p>
    <p>do you have any idea why refer-to user part can be empty in refer
      coming from teams ?<br>
    </p>
    <div class="moz-cite-prefix">On 11/05/2020 19:14, Ovidiu Sas wrote:<br>
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cite="mid:CAND0Lktb2yS-bp9fz_LJuZ83Hsbd75MRdcF-9w0zWj8eYYBMSQ@mail.gmail.com">
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        <div dir="auto">Microsoft’s SIP routing is RFC compliment.</div>
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      <div dir="auto">There’s no special routing for approved SBCs. The
        routing Is based on the type of SBC: B2BUA vs proxy, which
        again, is rfc complient.</div>
      <div dir="auto">For OpenSiPS, which is a proxy, all the
        configuration steps are very well outlined in the blog. No need
        to mess with Via or Contact headers! Follow the loose routing
        rules as outlined in the rfc and all is good.</div>
      <div dir="auto"><br>
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      <div dir="auto">Regards,</div>
      <div dir="auto">Ovidiu Sas</div>
      <div><br>
        <div class="gmail_quote">
          <div dir="ltr" class="gmail_attr">On Mon, May 11, 2020 at
            05:51 Slava Bendersky via Users <<a
              href="mailto:users@lists.opensips.org"
              moz-do-not-send="true">users@lists.opensips.org</a>>
            wrote:<br>
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                <div>Hello All,</div>
                <div>Microsoft is rely on approved sbc vendors, where 
                  most sbc are use VIA and headers to route traffic.
                  That why Contact header is important, also they use
                  from and to.</div>
                <div>Opensips is rely on route headers and use different
                  way to route it.</div>
                <div><br>
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                <div>volga629 </div>
                <div><br>
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                <hr id="m_-2318876661958670388zwchr">
                <div><b>From: </b>"John Quick" <<a
                    href="mailto:john.quick@smartvox.co.uk"
                    target="_blank" moz-do-not-send="true">john.quick@smartvox.co.uk</a>><br>
                  <b>To: </b>"OpenSIPS users mailling list" <<a
                    href="mailto:users@lists.opensips.org"
                    target="_blank" moz-do-not-send="true">users@lists.opensips.org</a>>,
                  <a href="mailto:james@ip-sentinel.com" target="_blank"
                    moz-do-not-send="true">james@ip-sentinel.com</a><br>
                  <b>Sent: </b>Monday, May 11, 2020 6:19:50 AM<br>
                  <b>Subject: </b>Re: [OpenSIPS-Users] OpenSIPS as
                  Teams SBC<br>
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                <div>I agree completely with Ovidiu.<br>
                  The Microsoft documentation says to use a FQDN in the
                  Contact header, but<br>
                  this is wrong when the SBC is acting as a SIP Proxy.<br>
                  The blog post on the OpenSIPS website explains that
                  actually the<br>
                  Record-Route header needs the FQDN.<br>
                  The one exception to this is the handling of OPTIONS
                  pings - for these,<br>
                  OpenSIPS is the end point so it must use a FQDN in
                  Contact.<br>
                  <br>
                  If you change the Contact header in call setup then
                  you risk breaking the<br>
                  path for sequential requests, such as ACK.<br>
                  If ACK does not reach its destination, the call drops
                  at one end after about<br>
                  20 seconds - exactly what you are seeing.<br>
                  <br>
                  I have not yet found a good way to capture TLS encoded
                  SIP. In theory, you<br>
                  can use sngrep with the -k option to identify the path
                  to the private key<br>
                  file.<br>
                  It would be necessary to start sngrep first, then
                  start (or restart)<br>
                  OpenSIPS. However, this never works for me.<br>
                  I had more success using the siptrace module to
                  capture the packets to a DB<br>
                  table. Presenting it as a sequence diagram may be
                  possible using the<br>
                  OpenSIPS Control Panel.<br>
                  Wireshark also has the ability to capture, decode and
                  present TLS encrypted<br>
                  SIP.<br>
                  Another option might be to mirror the traffic to Homer
                  in HEP format and<br>
                  then use Homer to create the sequence diagram.<br>
                  <br>
                  John Quick<br>
                  Smartvox Limited<br>
                  <br>
                  <br>
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      -- <br>
      <div dir="ltr" class="gmail_signature"
        data-smartmail="gmail_signature">VoIP Embedded, Inc.<br>
        <a href="http://www.voipembedded.com" target="_blank"
          moz-do-not-send="true">http://www.voipembedded.com</a></div>
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      <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>
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</pre>
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