Thank everybody!
Especially thank Brett very much for forwarding this to sipcore!

This issue has been clarified in sipcore forum.

Actually this is my misunderstanding.

If a server transaction is in proceeding state, and TU hands a 2xx response
to server transaction, server transaction should transition to accepted
state no matter if there is transport error or not.

Best Regards,
Caixia


On Tue, Jun 24, 2014 at 1:50 AM, Roman Shpount <[email protected]> wrote:

> Brett,
>
> This can probably be handled by timer C. The problem is that very few
> clients actually resend the last provisional response every minute to keep
> the transaction from expiring on timer C. In practice, application call
> timeouts are set to be much less then 3 minutes so that the entire cal gets
> hanged up and the whole transaction gets cancelled before timer C ever
> fires. My point is, there is a gap in SIP transaction state definition with
> INVITE transactions never expiring when in proceeding state, but in
> practice this is not a major problem since application call level timers
> typically terminate the whole call if it is not answered within reasonable
> time. So, this can be fixed but there is very little incentive for real
> world implementation to worry or care about this specification change.
>
> _____________
> Roman Shpount
>
>
> On Mon, Jun 23, 2014 at 7:14 AM, Brett Tate <[email protected]> wrote:
>
> > Hi Roman,
> >
> > Transaction state and call state are separate things.  However since I'm
> > not
> > sure what timer (proprietary or RFC defined) sipcore was expecting to be
> > used while stuck within Proceeding because of the RFC 6026 requirement, I
> > posted the question to sipcore.
> >
> > It will eventually show up in the archive.
> >
> > http://www.ietf.org/mail-archive/web/sipcore/current/maillist.html
> >
> >
> > -----
> >
> > From: Roman Shpount [mailto:[email protected]]
> > Sent: Monday, June 23, 2014 6:06 AM
> > To: Caixia Liu
> > Cc: Brett Tate; [email protected]
> > Subject: Re: [Sip-implementors] A Question about INVITE Server
> Transaction
> > in RFC 6026
> >
> > Caixia,
> >
> > I do not think specification missed anything. This is quite intentional.
> > There is no limit of how long the caller can be dialing the number (as
> > there
> > is no limit on how long the caller can stay connected on a SIP call). If
> > you
> > need to put a limit on this duration, this will have to be application
> > specific and does not need to be defined in the SIP spec. For instance
> you
> > can define that dial timeout when placing the call is 1 minute and that
> > will
> > limit the duration of the proceeding state. Or you can set the dial
> timeout
> > at 10 minutes. Or you can set this to be unlimited and let the caller
> hang
> > up when they are done waiting for the call to connect. This is really up
> to
> > you. The same way you can put maximum call duration at 24 hours and limit
> > calls this way or you can let the caller hang up when they are done
> > talking.
> > _____________
> > Roman Shpount
> >
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>
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