Subject: [Sip] Device ID callee capabilitiy

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 16 Jul 2003 11:17:27 -0400

Folks,

One of the issues I raised today during the meeting was on the utility 
of the uri-user and uri-domain parameters in 
draft-ietf-sip-callee-caps. The primary purpose that these serve is a 
means of identifying a UA instance. In order to accomplish 
applicaitons like assisted call transfer, a UA would send INVITE to 
the AOR of the transfer target, and include an Accept-Contact with the 
uri-user and uri-domain equal to those of the UA instance.

Now, it turns out that uri-user and uri-domain are not very helpful 
when used this way. GRUU is a better approach. However, thats almost a 
secondary issue.

The primary issue is that uri-user and uri-domain are ugly, and they 
repeat information already in the registration. The suggestion, made 
by Paul, was to instead define a device-id attribute. This ID would be 
long lived - burned into firmware of a device, perhaps. It would be 
included in a registration as a unique ID for the device or software 
instance, as the case may be.

You could use this callee capability attribute for the assisted 
transfer just as you could use uri-user and uri-domain. It has the 
same problems that still make GRUU a better solution. However, during 
the meeting, folks like the idea of a device-id attribute as something 
useful for lots of other applications.

So, I would like to invite comment and discussion on (1) whether you 
like the idea of replacing the uri-user and uri-domain attributes with 
device-id (a better name may be needed, like instance-id), (2) what 
kind of usages you had in mind for it, for good or for evil.

Thanks,
Jonathan R.
-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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