Hi Valdemar ,

I am pasting few lines from 3261. Hope this will clarify your doubt.

*17.1.2.1 Overview of the non-INVITE Transaction

   Non-INVITE transactions do not make use of ACK.  They are simple
   request-response interactions.  For unreliable transports, requests
   are retransmitted at an interval which starts at T1 and doubles until
   it hits T2.  If a provisional response is received, retransmissions
   continue for unreliable transports, but at an interval of T2.  The
   server transaction retransmits the last response it sent, which can
   be a provisional or final response, only when a retransmission of the
   request is received.  This is why request retransmissions need to
   continue even after a provisional response; they are to ensure
   reliable delivery of the final response.*


Regards,
Sumit Jindal

On Thu, Nov 24, 2011 at 11:51 AM, Aman Aggarwal
<[email protected]>wrote:

> Hi Valdemar,
>
> That is possible. On receiving 100 Trying, UPDATE retransmissions would
> stop. However, you have to start a guard timer at application level to
> handle a scenario when no response is received from the server.
>
> regards,
> Aman Aggarwal
> Aricent.
>
> -----Original Message-----
> From: [email protected] [mailto:
> [email protected]] On Behalf Of Pavesi,
> Valdemar (NSN - US/Irving)
> Sent: Wednesday, November 23, 2011 8:59 PM
> To: [email protected]
> Subject: [Sip-implementors] UPDATE delay to send 200ok final response
>
> Hello ,
>
>
> We have to send update to change the session :
>
> a)      We want it
> 1  50.987832   10.48.4.2             10.52.39.194          SIP/SDP
> Request: UPDATE sip:10.52.39.194:5060;transport=UDP, with session
> description
> 2   50.987832   10.52.39.194          10.48.4.2             SIP/SDP
> Status: 200 OK, with session description
>
>
>
> b)      But the remote sip endpoint  have a kind of SAVE-GUARD mechanism
> that will allow to change the session just after 3.5 seconds
>
>   1815 50.987832   10.48.4.2             10.52.39.194          SIP/SDP
> Request: UPDATE sip:10.52.39.194:5060;transport=UDP, with session
> description
>   1820 51.491327   10.48.4.2             10.52.39.194          SIP/SDP
> Request: UPDATE sip:10.52.39.194:5060;transport=UDP, with session
> description
>   1824 52.501307   10.48.4.2             10.52.39.194          SIP/SDP
> Request: UPDATE sip:10.52.39.194:5060;transport=UDP, with session
> description
>   1828 53.987731   10.52.39.194          10.48.4.2             SIP/SDP
> Status: 200 OK, with session description
>
>
>
> c)       Do you think we can have it ?
>
>   1815 50.987832   10.48.4.2             10.52.39.194          SIP/SDP
> Request: UPDATE sip:10.52.39.194:5060;transport=UDP, with session
> description
>   1828 50.987835    10.52.39.194          10.48.4.2             SIP/SDP
> Status: 100 trying
>  .
>  3.5 seconds later
>  .
>  .
>  1828 53.987731   10.52.39.194          10.48.4.2             SIP/SDP
> Status: 200 OK, with session description
>
>
>
> ++
>
> 21.1.1 100 Trying
>
>   This response indicates that the request has been received by the
>   next-hop server and that some unspecified action is being taken on
>   behalf of this call (for example, a database is being consulted).
>   This response, like all other provisional responses, stops
>   retransmissions of an INVITE by a UAC.  The 100 (Trying) response is
>   different from other provisional responses, in that it is never
>   forwarded upstream by a stateful proxy.
> ++++
>
>
> Regards!
> Valdemar
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-- 
Regards,
Sumit Jindal
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