[SIPForum-discussion] The missed Call with PRACK terminated using BYE or Cancel

[Banda, Srinivas (Srinivas)]

According to the Section 15 in RFC-3261:

15 Terminating a Session

   This section describes the procedures for terminating a session
   established by SIP.  The state of the session and the state of the
   dialog are very closely related.  When a session is initiated with an
   INVITE, each 1xx or 2xx response from a distinct UAS creates a
   dialog, and if that response completes the offer/answer exchange, it
   also creates a session.  As a result, each session is "associated"
   with a single dialog - the one which resulted in its creation.  If an
   initial INVITE generates a non-2xx final response, that terminates
   all sessions (if any) and all dialogs (if any) that were created
   through responses to the request.  By virtue of completing the
   transaction, a non-2xx final response also prevents further sessions
   from being created as a result of the INVITE.  The BYE request is
   used to terminate a specific session or attempted session.  In this
   case, the specific session is the one with the peer UA on the other
   side of the dialog.  When a BYE is received on a dialog, any session
   associated with that dialog SHOULD terminate.  A UA MUST NOT send a
   BYE outside of a dialog.  The caller's UA MAY send a BYE for either
   confirmed or early dialogs, and the callee's UA MAY send a BYE on
   confirmed dialogs, but MUST NOT send a BYE on early dialogs.

So the behavior mentioned in your call scenario is correct.

Regards
Srinivas

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of AOEKING
Sent: Saturday, January 25, 2014 1:43 PM
To: Murali ZTE
Cc: discussion at sipforum.org
Subject: Re: [SIPForum-discussion] The missed Call with PRACK terminated using BYE or Cancel

Hi Murali,

Here's what I found from the specification (http://tools.ietf.org/html/rfc3262#page-6)

"The provisional response MUST establish a dialog if one is not yet created."

According to above statement the client behavior is correct.

Thanks,
Nuwan

On Sat, Jan 18, 2014 at 1:19 PM, Murali ZTE <muralizte at hotmail.com<mailto:muralizte at hotmail.com>> wrote:
Hello Guys,

I have one query regarding PRACK for the following scenario  my SIP client sending BYE message instead of Cancel.Is it right behavior? because the session is not established for the initial INVITE.or its behaving correctly because of PRACK.Could anyone explain this behaviour ?

UAC-------INVITE-------------->UAS
UAC<-----1xx------------------>UAS
UAC<-----180(Rseq)----------UAS
UAC--------PRACK(Rack)--->UAS
UAC<-----200 OK(PRACK)--UAS
UAC-------- BYE-------------->UAS


Thanks and Regards
Murali

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