Subject: [Simple] tel as device identifier

From: Henning Schulzrinne <[email-masked]>
Date: Sat, 18 Jun 2005 12:42:40 -0400

Currently, there is no really good device identifier (device-id), as 
none of the obvious candidates (IMSI, MAC address, etc) currently have a 
URN definition. In order to speed deployment, one quick-and-easy 
suggestion is to use the tel URL. While this does not always identify a 
single device, in many practical cases of interest, it does. Examples 
where this is likely to work reasonably well include mobile phones and 
residential analog phones (i.e., without ENUM).

Comments?

Henning

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From: Paul Kyzivat <[email-masked]>
Date: Sat, 18 Jun 2005 14:01:15 -0400

Henning,

I think the problem is that presumably the device itself must decide if 
this can be used as a device-id. I don't know how the device would be 
able to decide that it is the only one that will be trying to use the 
phone number as a device id.

If it is a human deciding to do this then I think it can work.

	Paul

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From: Henning Schulzrinne <[email-masked]>
Date: Sat, 18 Jun 2005 15:08:16 -0400

> If it is a human deciding to do this then I think it can work.

Initially, I suspect that most devices won't do any publishing on their 
own, so this will have to be entered manually. I agree that this is not 
a long-term or universal solution, but we lack deployable alternatives.

For current cell phones, 'tel' should work reasonably well. As far as I 
know, each cell number is assigned to exactly one device at a time.

Even for residential phones, while there might be multiple devices on a 
single piece of wire, the phone company (ILEC) could certainly assign 
this as an identifier. These multiple devices act essentially as if they 
were one - there's no way to reach just one of them. (Indeed, this 
application motivates my question.)

Henning

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From: Cullen Jennings <[email-masked]>
Date: Tue, 21 Jun 2005 11:31:00 -0700

tel is definitely not a unique device identifier - i have many devices with
the same tel. Why not just use an UUID  URN as a device id.

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From: Henning Schulzrinne <[email-masked]>
Date: Tue, 21 Jun 2005 20:08:45 -0400

> the same tel. Why not just use an UUID  URN as a device id.

My vague recollection was that UUID were considered unsuitable and 
therefore removed from the data model draft. I'm looking for other 
deployable solutions.

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From: Dean Willis <[email-masked]>
Date: Tue, 21 Jun 2005 20:09:59 -0500

> therefore removed from the data model draft. I'm looking for other 

IMSI, IMEI, ESN, MEID, and ethernet MAC addresses all come to mind as 
relatively unique device identifiers.

--
Dean

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From: Henning Schulzrinne <[email-masked]>
Date: Tue, 21 Jun 2005 21:14:31 -0400

> relatively unique device identifiers.

Agreed, but do URN forms of these exist? I think it would be quite 
useful if somebody could define

urn:imsi:
urn:imei:
urn:mac:

etc.

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From: Cullen Jennings <[email-masked]>
Date: Wed, 22 Jun 2005 13:09:07 -0700

>> relatively unique device identifiers.

I might be wrong but I think the answer is yes they do and it is called uuid

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 22 Jun 2005 17:38:44 -0400

It seems like we had this discussion before. The conclusion was, if I 
recall correctly, that the UUID "experts" advised Jonathan that this 
would not be an appropriate device identifier since the UUID contains 
time-dependent components (see 
http://www.ietf.org/internet-drafts/draft-mealling-uuid-urn-05.txt, 
Section 4.1.2) and one would have to kludge some pseudo-UUID that set 
these values to, say, zero.

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From: Cullen Jennings <[email-masked]>
Date: Wed, 22 Jun 2005 14:44:52 -0700

Yes, but I think that was about trying to correlate things from various
applications on same device. It seem the case you are interesting in you
just want a stable unique identifier for each application on the device so
I'm not sure that I see any problem with the time based stuff. Anyways, I
don't know if UUID is right or not but it seemed to me that tel was not
right.