Subject: [Sipping] RE: draft-johnston-enum-conf-service-00

From: "Johnston, Alan" <[email-masked]>
Date: Thu, 17 Feb 2005 03:26:15 +0000

Paul,

Thanks for your comments. 

In a scenario in which the E.164 number is part of a SIP conference,
then there would be both 'sip' and 'conf-uri' ENUM service URIs, and
they would be the same.  The advantage of having the 'conf-uri' in
addition to the 'sip' is that it effectively already includes the
"isfocus" feature tag, telling the UA that the SIP URI is a conference
URI.  Of course, the UA could do an ENUM query, get the 'sip' URI then
do an OPTIONS to the URI to find out that it is a conference, but this
is less streamlined.

There are other types of conferences in which there may not be SIP media
but SIP or other protocol URIs could be used for conferencing services.
For these, there would be no 'sip' service URI, but there could be a
'conf-uri' service SIP URI.  The UA could then SUBSCRIBE to this
conference URI, but the media, would be routed over the PSTN. (Any
INVITEs sent to this conference URI would be politely redirected to the
E.164 number in a tel URI.)

I can't think of any scenarios in which if they were both present, the
'sip' and 'conf-uri' URIs would be different.

Thanks,
Alan Johnston
sip:[email-masked]

> -----Original Message-----
> From: Paul Kyzivat [mailto:[email-masked]] 
> Sent: Wednesday, February 16, 2005 5:13 PM
> To: Johnston, Alan
> Cc: 'sipping'
> Subject: Re: draft-johnston-enum-conf-service-00
> 
> 
> Alan,
> 
> I'm confused by this draft. I'm asking on sipping because I 
> suspect that 
> is the best place to discuss. (Maybe xcon, but I think that 
> is not for 
> the sip part of conferences.)
> 
> If I have an E.164 number that has an Enumservice entry for 
> "conf-uri", 
> it must be a permanent conference. For non-conference-aware 
> clients to 
> call this conference, it probably has an Enum entry for "sip". (Or 
> h.323...) What added benefit is provided by an entry for 
> "conf-uri"? If 
> the "conf-uri" is a sip uri, will it have a different value that an 
> entry for sip? If so, why?
> 
> 	Paul
> 

_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
Use [email-masked] for new developments of core SIP

---

From: Paul Kyzivat <[email-masked]>
Date: Thu, 17 Feb 2005 09:32:38 -0500

Johnston, Alan wrote:
> they would be the same. 

OK. I would have been more confused if they were different.

> The advantage of having the 'conf-uri' in

The advantage seems at best marginal. This only makes sense if the 
number is more or less permanently assigned to a conference, rather than 
being the number of somebody's phone that might sometimes be a 
conference. So there is a fair chance that the caller already knows it 
is a conference a priori, and if not, will find out as soon as a call is 
established.

I'm scratching my head more because I can't imagine too many cases where 
a phone number would be dedicated to a conference. I can imagine 
(because it is common) having a phone number dedicated to a conference 
*server*. But that is not the same thing. When I call one of those I 
have to interact with an IVR and provide a separate id of a specific 
conference. So the number itself does not designate a conference and 
couldn't be bound to a conf-uri.

> E.164 number in a tel URI.)

I can almost buy this as a hypothetical, though I'm dubious that I will 
ever encounter such a thing in practice.

I'd need to see a much more compelling case before I would bother 
implementing code to take advantage of this.

> 'sip' and 'conf-uri' URIs would be different.

That's comforting.

	Thanks,
	Paul