[SR-Users] SIP basic flow question: R-URI in ACK

[Yufei Tao]

Hi Daniel,

Thank you very much for clarifying!

Cheers,
Yufei

On 30 Apr 2019 at 08:10, <Daniel-Constantin Mierla <miconda at gmail.com>>
wrote:

Hello,

there is an errata for that RFC, but it refers only to the BYE, where it
adds back the transport=tcp, but the ACK R-URI should follow the same
rules, see:

  * https://www.rfc-editor.org/errata/eid5294

Cheers,
Daniel
On 28.04.19 22:54, Yufei Tao wrote:

Hi,



I have a question regarding basic SIP flow for establishing a call session,
and wonder if anyone can help me clarify.



For normal call set up, INVITE-OK-ACK, from RFC3261, I believe the ACK’s
R-URI should be a copy of the Contact header of the OK message.



However in RFC3665 sections 3.1 and 3.2 for example, the ACK’s R-URI missed
the parameters from the Contact header of the OK, e.g.



In OK the Contact header is:

   Contact: <sip:bob at client.biloxi.example.com;transport=tcp>
<sip:bob at client.biloxi.example.com;transport=tcp>



And  ACK the R-URI is:

ACK sip:bob at client.biloxi.example.com SIP/2.0



Which has got the parameter ‘transport=tcp’ removed – why is this?



In this case if the proxy connected to Bob handles ACK in the usual way as
it would for all in-dialog requests, i.e. based on routing headers only and
not extra processing, it’ll try to relay the ACK message to Bob using the
default transport UDP which is not expected and will fail.



Can anyone help explain why the parameters are removed in RFC3665 examples
please? Have I missed anything? Thank you very much!



Yufei

_______________________________________________
Kamailio (SER) - Users Mailing
Listsr-users at lists.kamailio.orghttps://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users

--
Daniel-Constantin Mierla -- www.asipto.comwww.twitter.com/miconda --
www.linkedin.com/in/miconda
Kamailio World Conference - May 6-8, 2019 -- www.kamailioworld.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.kamailio.org/pipermail/sr-users/attachments/20190430/8567971f/attachment.html>