H.323 (8.1) Phase A - Call Setup
Chris Wayman Purvis
cwp at isdn-comms.co.uk
Fri Jul 20 09:02:19 EDT 2001
Ah! The reasoning becomes clear - thanks Paul!
Nevertheless, Pete is right. Given that the term "endpoints" can include
answering machines this needs some careful rewording!
Paul E. Jones wrote:
> 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.
> ----- 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
>> 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
>> 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
>> timeout for the sending endpoint.
>> I think the sentence should read:
>> "If an endpoint can respond to a Setup message with a Connect, Alerting,
>> 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
>> (second para).
>> Peter Price
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Dr Chris Purvis -- Development Manager
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