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<p>Hello,<br>
</p>
<br>
<div class="moz-cite-prefix">On 30.05.17 20:02, Phil Lavin wrote:<br>
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<p class="MsoNormal">Hi all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Theoretical question about the role of a
Kamailio proxy which is also a registration server for UAs.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Assuming a B2BUA on IP 1.2.3.4 behind the
Kamailio proxy. Kamailio receives an INVITE from this B2BUA
with From and Contact as something like
<a moz-do-not-send="true" href="sip:4321@1.2.3.4">sip:4321@1.2.3.4</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When Kamailio routes the INVITE to that UA,
is it Kamailio’s responsibility to change the domain part of
the From and/or Contact to itself (e.g.
<a class="moz-txt-link-freetext" href="sip:4321@proxy.mytld.com">sip:4321@proxy.mytld.com</a>)?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The question has arisen from Polycom missed
call “call back” behaviour. When issuing a call back from a
Polycom, following a missed call, it sends the call directly
to the full URI in the INVITE’s From (or maybe Contact… I’ve
not fully tested yet). As such the call is sent to the B2BUA,
which UAs do not have access to, and thus times out.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I suspect here the answer is “no”, and the
Polycom must be configured to force all outbound calls through
the proxy… but thoughts welcome.<o:p></o:p></p>
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</blockquote>
iirc, by specs, the proxy should not change the contact, many
devices complain if they receive a R-URI with an address that was
not set by them as contact in an earlier request.<br>
<br>
In you case, very likely it is the From header that is used to dial
back, being a common behaviour of SIP endpoints.<br>
<br>
From header should not be changed either, but without doing it a lot
of things don't work as expected by users. That's why we have
uac_replace_from() exported by uac module.<br>
<br>
Usually, all the nodes (proxy, b2bua, media servers, a.s.o.) in the
core platform should use a domain instead of their IP address when
constructing From/To headers, the domain pointing at the edge proxy,
so any call back will end up there.<br>
<br>
Cheers,<br>
Daniel<br>
<pre class="moz-signature" cols="72">--
Daniel-Constantin Mierla
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Kamailio Advanced Training - <a class="moz-txt-link-abbreviated" href="http://www.asipto.com">www.asipto.com</a>
Kamailio World Conference - <a class="moz-txt-link-abbreviated" href="http://www.kamailioworld.com">www.kamailioworld.com</a></pre>
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