Subject: [Sip] Service Examples - Single Line Extensions

From: [email-masked]
Date: Wed, 28 Nov 2001 15:53:58 EST

Regarding draft-ietf-sip-service-examples.03:

Section 2.10 Single Line Extension
I don't understand the application of a service which "rings several 
extensions in sequence". The requirement to emulate a group of extensions 
would be to simultaneously ring all.
The reference to "help desk/call center" further confuses the issue of Single 
Line Extension. In fact, "extensions" are typically used for individual 
users, for example, when a couple of office mates share one phone number. 
This is no different than the Home Extension case. Larger groups, such as 
might be used for help desk/call center applications, use a much more 
complicated feature set than "extensions" or what is shown in Section 2.11.

Section 2.11
States that the signaling for Single Line Extension and Find-Me is the same. 
These should be two different services and fundamentally different signaling. 
Single Line Extension must work differently than shown. I presume that 
"Forking" is required here, and the INVITEs are simultaneously sent to a 
group of devices that have been somehow defined as belonging together 
("extensions" in the mind of the user). Find-Me, on the other hand, could 
sequentially signal to a list of locations which are not "extensions". They 
are unrelated devices. (In fact, one of the sequential attempts in the 
Find-Me chain could be to ring a group of extensions.)

Mike Pierce
Artel

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From: Alan Johnston <[email-masked]>
Date: Wed, 28 Nov 2001 15:59:35 -0600

Mike,

See my comments below.  This new version of this draft has only minor changes
since the last - changes to how hold is signaled in SDP and changes to the syntax
of REFER messages.

Look for more activity with this draft soon, using many useful concepts from
Jonathan's SIP Event Package draft.
(http://search.ietf.org/internet-drafts/draft-rosenberg-sip-call-package-00.txt)

Thanks,
Alan. Johnston
sip:[email-masked]
WorldCom

> complicated feature set than "extensions" or what is shown in Section 2.11.

I agree - the wording on this section is badly out of date.  See the above draft
for details on this service.

> Find-Me chain could be to ring a group of extensions.)

Again, I agree.  This section will be substantially reworked soon.