No, 200OK retransmission is stopped until ACK's arrival or 64*T1. PRACK has no 
impact on this.
Check RFC3261 sec 13.3.1.4

fyi
-Rockson 

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Siddhardha Garige
Sent: Thursday, November 06, 2008 3:16 PM
To: [email protected]
Subject: [Sip-implementors] controlling 200OK retransmissions.

Hello all,

I have a question regarding retransmission of 200OK. 

Proxy can send 100 Trying to stop retransmission on invites on UAC is there any 
way to control retransmission of 200OK from UAS?

Is this a valid senario? Will PRACK stop retransmission of 200Ok messages?

UAC ---------------Proxy --------------------------UAS

--------Invite--------------------------------------------->

<------------------------------100 trying-----------------

<--------------------------------180 ringing--------------

<--------------------------------200 Ok---------------------

                       ------------PRACK---------------->
                      
                      <-------------200 OK (prack------

-----------------------------------ACK-------------------->

<-------------------------------rtp--------------------------->

RFC 3262
The reliability mechanism works by mirroring the current reliability
   mechanisms for 2xx final responses to INVITE.  Those requests are
   transmitted periodically by the Transaction User (TU) until a
   separate transaction, ACK, is received that indicates reception of
   the 2xx by the UAC.  The reliability for the 2xx responses to INVITE
   and ACK messages are end-to-end.  In order to achieve reliability for
   provisional responses, we do nearly the same thing.  Reliable
   provisional responses are retransmitted by the TU with an exponential
   backoff.  Those retransmissions cease when a PRACK message is
   received.  The PRACK request plays the same role as ACK, but for
   provisional responses.  There is an important difference, however.
   PRACK is a normal SIP message, like BYE.  As such, its own
   reliability is ensured hop-by-hop through each stateful proxy.  Also
   like BYE, but unlike ACK, PRACK has its own response.  If this were
   not the case, the PRACK message could not traverse proxy servers
   compliant to RFC 2543 [4]Any help is appreciated.

Thanks
Sid




      
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