hi,
In the call flow example of 20.5, a BYE has not been sent before the ACK.
The reason for this is not that the protocol prohibits it. It is because the
user Bell doesnot know who among the 2 persons who answered to his INVITE is
the 'real' Watson. Only after the media stream starts and he is able to talk
to both the persons has he been able to ascertain to whom he wants to talk
to ( X or Y). So, how can this example be taken to be saying that an ACK
is mandatory ?
Also, what about section 1.4.4 of the RFC2543 which specifically says "If
the caller no longer wants to participate in
the call, it sends a BYE request instead of an ACK." Has this been
contradicted elsewhere? Also, should the UA not retransmitting the 200 OK ,
once it receives a BYE? Is there anything specific for or against this in
the bis-03? if so, where?
One more thing the RFC says that though an ACK completes a succesful
'session establishment' it says that an ACK comprises a transaction of its
own?
thanks and regards,
gautham
----- Original Message -----
From: Vijay Gurbani <[EMAIL PROTECTED]>
To: Gautham A N <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Friday, June 08, 2001 9:01 AM
Subject: Re: [Sip-implementors] doubt in BYE and ACK
> Gautham A N wrote:
> >
> > hi,
> > if after you have got a final response of 200 OK and you want to
> > terminate the call by sending a BYE instead of sending an ACK. This is
> > stated in the rfc2543 : "If the caller no longer wants to participate in
> > the call, it sends a BYE request instead of an ACK." in section 1.4.4.
> > Also the bis-03 says that u should not send a BYE before getting a final
> > response. It does not say that u must send an ACK first and then
terminate
> > the call using a BYE.
>
> I am pretty sure it does (check out the call flows in section 20.5, -03
> bis). UAC MUST send an ACK to a 2xx and then a BYE if it does not want to
> sustain the call (or that call-leg).
>
> In any case, look at it logically: the spec defines a successful session
> establishment as INVITE/200 OK/ACK (ACK is part of the INVITE transaction,
> although a separate method). Furthermore, the spec specifies that a UAS
> will continue to retx 200 OK (INVITE) until a) it gets an ACK, or b) its
> retx counter runs out. Getting a BYE to a 200 OK (INVITE) should not stop
a
> UAS retx'ing the 200 OK (INVITE).
>
> Regards,
>
> - vijay
> --
> Vijay K. Gurbani vkg@{lucent.com,research.bell-labs.com,acm.org}
> Internet Software and eServices Group
> Lucent Technologies/Bell Labs Innovations 263 Shuman Blvd., Rm 1A-413
> Naperville, Illinois 60566 Voice: +1 630 224 0216 Fax: +1 630 713
0184
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