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<p class="MsoNormal"><span style="font-size:11.0pt">RFC 3261 is explicit that the From and To headers in a response MUST be equal to those in the request, with the exception of the potential addition of a tag in the To header if not already present.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><a href="https://www.rfc-editor.org/rfc/rfc3261.html#section-8.2.6.2">https://www.rfc-editor.org/rfc/rfc3261.html#section-8.2.6.2</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">Ben Newlin</span><span style="font-size:11.0pt"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Users <users-bounces@lists.opensips.org> on behalf of Johan De Clercq <Johan@democon.be><br>
<b>Date: </b>Wednesday, April 10, 2024 at 9:44 AM<br>
<b>To: </b>OpenSIPS users mailling list <users@lists.opensips.org><br>
<b>Subject: </b>[OpenSIPS-Users] on from and to header.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Calibri",sans-serif;color:#B60000"> EXTERNAL EMAIL - Please use caution with links and attachments <o:p></o:p></span></b></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">This is more a protocol question then anything else. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">A sends a call B <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">INVITE <a href="mailto:B@5.6.7.8">
B@5.6.7.8</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">from: <<a href="http://sip:A@1.2.3.4:5060">sip:A@1.2.3.4:5060</a>>;tag=1<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">to: <<a href="mailto:sip%3AB@5.6.7.8">sip:B@5.6.7.8</a>><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">call-id: 1<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">......<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">B responds with from and to in e164 format<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">200 OK<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">from: <<a href="http://sip:+32A@1.2.3.4:5060">sip:+32A@1.2.3.4:5060</a>>;tag=1<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">to: <<a href="mailto:sip%3A%2B32B@5.6.7.8">sip:+32B@5.6.7.8</a>>; tag=2<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">call-id: 1<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">My gut feeling says to me that A will not like this and hence that B should respong with A and B instead of +32A and +32B. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">But can somebody explain me why or why not? <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Best regards, Johan. <o:p></o:p></span></p>
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