AW: H.323 (8.1) Phase A - Call Setup

[Guntram Diehl]

Hi all,
I would recommend to read Q.931. This gives a lot of background information
about the use of the different messages.
Guntram

> -----Ursprüngliche Nachricht-----
> Von: Peter Price [mailto:PeterP at VEGASTREAM.COM]
> Gesendet: Freitag, 20. Juli 2001 15:37
> An: ITU-SG16 at MAILBAG.INTEL.COM
> Betreff: Re: H.323 (8.1) Phase A - Call Setup
>
>
> Paul,
>
> in fact, on further reflection, your second paragaraph
> highlights the error
> in (8.1)
> We both agree Alerting should be sent to the caller as soon
> as the callee's
> phone is ringing but the text opens the door for someone to send Call
> Proceeding and then not ever send Alerting.
>
> It becomes clearer to me that the original intent was almost certainly
> "If an endpoint can respond to a Setup message with a Connect within 4
> seconds, it is not required to send the Alerting message."
> Reference to Call Proceeding is incorrect and to Release Complete
> irrelevent.
>
> I'm not sure what should be done to clarify the purpose of
> Call Proceeding.
> I think it being optional for terminal devices has led people
> to ignore its
> correct use in gateways which are an important part of the
> network.  Perhaps
> this need a separate thread.
>
> Peter
>
> > -----Original Message-----
> > From: Peter Price [mailto:PeterP at VEGASTREAM.COM]
> > Sent: 20 July 2001 14:05
> > To: ITU-SG16 at mailbag.cps.INTEL.COM
> > Subject: Re: H.323 (8.1) Phase A - Call Setup
> >
> >
> > Paul,
> >
> > I forgot to say that I agree with your second paragraph with
> > the proviso
> > that it might take more than 4 seconds to send the Alerting.
> > Call Proceeding is not a substitue for Alerting its just an
> > indication that
> > the caller should not give up too quickly.
> >
> > Pete
> >
> > > -----Original Message-----
> > > From: Paul E. Jones [mailto:paulej at PACKETIZER.COM]
> > > Sent: 20 July 2001 12:48
> > > To: ITU-SG16 at mailbag.cps.INTEL.COM
> > > Subject: Re: H.323 (8.1) Phase A - Call Setup
> > >
> > >
> > > Peter,
> > >
> > > Alerting was the intent.  Call Proceeding not produce a
> > > ringing sound in the
> > > caller's ear.  H.323 devices have to be able to send an
> > > Alerting, though
> > > they're not required to do so if they can send a Connect
> > > within 4 second.
> > > The 4 seconds is the T303 timeout and the T303 timer is
> > disabled when
> > > receiving Alerting, too... not just Call Proceeding.
> > >
> > > The ideas are related, but independent.  What we have seen
> > > some folks do is
> > > send a Call Proceeding to the caller and then nothing
> else until the
> > > connect.  The result is that the calling party hears silence
> > > for a very long
> > > time: that's not good.
> > >
> > > Paul
> > >
> > > ----- Original Message -----
> > > From: "Peter Price" <PeterP at VEGASTREAM.COM>
> > > To: <ITU-SG16 at mailbag.cps.INTEL.COM>
> > > Sent: Friday, July 20, 2001 6:54 AM
> > > Subject: H.323 (8.1) Phase A - Call Setup
> > >
> > >
> > > > Hi folks,
> > > >
> > > > I think I may have found some incorrect text in H.323 8.1
> > > >
> > > > The same text appears in both V3 and V4 so I suspect nobody
> > > has commented
> > > > before.
> > > >
> > > > In the paragraph beginning:
> > > > "An endpoint shall be capable of sending the Alerting
> > message. ..."
> > > >
> > > > it goes on to say:
> > > > "If an endpoint can respond to a Setup message with a
> > Connect, Call
> > > > Proceeding, or Release Complete within 4 seconds, it is not
> > > required to
> > > send
> > > > the Alerting message. An endpoint sending the Setup message
> > > can expect to
> > > > receive either an Alerting, Connect, Call Proceeding, or
> > > Release Complete
> > > > message within 4 seconds after successful transmission."
> > > >
> > > > I believe the first sentence here should really be
> discussing the
> > > > requirement to send a Call Proceeding (not Alerting) message.
> > > > The period of 4 seconds in the last sentence is related to
> > > T303 which is
> > > > specifically terminated by a Call Proceeding message in
> > > order to extend
> > > the
> > > > timeout for the sending endpoint.
> > > >
> > > > I think the sentence should read:
> > > > "If an endpoint can respond to a Setup message with a
> > > Connect, Alerting,
> > > or
> > > > Release Complete within 4 seconds, it is not required to
> > > send the Call
> > > > Proceeding message."
> > > >
> > > > This is then consistent with the use of Call Proceeding
> > described in
> > > 8.1.8.2
> > > > (second para).
> > > >
> > > > Peter Price
> > > >
> > > >
> > >
> >
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> > >
> > >
> >
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> >
> >
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