Please see inline comments.

Neeraj Jain
BayPackets Technologies

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of jay prakash
dubey
Sent: Friday, September 30, 2005 12:26 PM
To: Sip-Implementors
Subject: [Sip-implementors] Query regarding 183 provisional response.

  
Hi all,

I am having one basic doubt in Prvisional response.If 180 ringing and 183
session progress both came from UAS to UAC.

 -----------INVITE+SDP------------------->
 <----------183 Session progress(SDP)---------
 ------------PRACK----------------------->
 <------------180 Ringing(SDP)---------------- 
<------------200 Ok (for PRACK)---------------
<------------200 Ok (for INVITE)--------------
 -------------------- --------------ACK( for Invite)---------->

1. what happen if 200 Ok for PRACK doesn"t recieve.call droped or not?

[NEERAJ] UAS in this flow is violating RFC3262 which says that a UAS must
not respond with final response to INVITE until there is an outstanding
provisional response containing SDP (which is 180 Ringing in this case).
Hence 200 Ok (for INVITE) must not be sent before the PRACK is received for
180 Ringing.

2. if 183 and 180 both has SDP than when final SDP negotiation can be done
in 200 OK (PRACK)?

[NEERAJ] Again as per RFC3262, SDP in 180 must be same as that in 183 unless
PRACK (183) contains additional offer from UAC. In later case, 180 must have
the same SDP as 200 OK (PRACK).

can any body clarify this call flow as in my application Early media is
must....

Thanks and regards
Jay

   



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