Subject: Re: URL Generalization for Portability (was TRIP)

From: Sean Olson <[email-masked]>
Date: Tue, 4 Jan 2000 18:01:02 -0600 (CST)

> Our application of the tel URL is slightly different. We are
> not using them
> to actual dial numbers from web pages. Rather, they point to resources
> in the PSTN. In
> that sense, I agree with Adam that what I think we want is for them to
> be uniform, so
> that they are resolvable from everywhere. This means they should either
> be international
> numbers, or be sip URLs which indicate where to go to get them resolved.
> 

But you can do this with the tel: URL as well by providing the tsp parameter.
The main distinction that I see between the sip: and tel: URLs is that
with the tel: URL, you know DEFINITIVELY that the resource that you are
referring to is a PSTN telephone. With the sip: URL this becomes trickier.
Are you referring to an IP/PC SIP client with a numeric ID that is 
convenient to dial from a plain black phone, or are you actually 
referring to a genuine PSTN terminal? The distinction is (usefully) blurred.

> So, in the case of a gateway sending just dialed digits to a proxy, I
> argued that we should use a SIP URL and put the contexts and stuff into
> the user portion. Several folks complained about that; is it more
> palatable to use the phone-context from the tel URL as part of the SIP
> URL?
> 
> sip:[email-masked];phone-context=0000034
>

It seems more logical, IMHO, to stuff everything into the user portion.
This allows you to easily distinguish between parameters directly
related to the user and parameters related to, for example, the 
preferred SIP transport.

> -Jonathan R.
> 
> -- 
> Jonathan D. Rosenberg                       200 Executive Drive
> Chief Scientist                             Suite 120 
> dynamicsoft                                 West Orange, NJ 07052
> [email-masked]                     FAX:   (732) 741-4778
> http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
> http://www.dynamicsoft.com
> 

-----------------------------------------------------------------
Sean Olson            mailto:[email-masked]
Ericsson Inc.         tel:(972)583-5472 
                      fax:(972)669-0154

---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 05 Jan 2000 00:18:28 -0500

> But you can do this with the tel: URL as well by providing the tsp parameter.

I think it means something different in the context of the tel URL. In
the tel URL, it would indicate that the call should be routed over the
circuit switched network of the telco indicated in the tsp parameter
(thats my interpretation, at least). With the SIP URL, the domain name
is used to obtain the address of a server to send the request to, that
server being the only server capable of resolving the name on the LHS of
the @ sign in the URL. These are really different, and when using
private dialing plans, I think the meaning is more in line with the SIP
URL form. Syntactically, its really no different and doesn't matter.

> referring to a genuine PSTN terminal? The distinction is (usefully) blurred.

But in the case we are discussing, we really don't know. All we know is
that the gateway has dialed some string of digits.

-Jonathan R.