Subject: Re: [Iptel] Comments on trunk group draft

From: [email-masked]
Date: Thu, 22 Jan 2004 12:01:53 EST

In a message dated 1/21/2004 6:09:22 PM Romance Standard Time, [email-masked] 
writes:

Insofar as the tel URI has been used to describe dial strings,
Calling Party Category (CPC) parameter, number portability and
freephone, I don't see the disadvantage of using it to describe
other telephony-related machinations like trunk groups.

[MAP] Yes, that's true, which means that, before the tel:uri draft is 
approved, it should be renamed from "The tel URI for Telephone Numbers"
to something like "The tel URI for general purpose telephony-related 
information"

In a message dated 1/21/2004 6:09:22 PM Romance Standard Time, [email-masked] 
writes:

[MAP] > The "Phone-context" parameter caused seemingly endless 
> discussions with the tel:uri and will probably do so here. I have no 
> idea what function it serves across interface "a" in the above.

[VKG] It probably serves little, if any, function in interface "a"; but
if it could serve a purpose if a proxy P1 sends a request to another
proxy P2 in a different domain using trunk groups pertinent to
P2's domain.  How P1 knows about these trunk groups is outside the
scope of this I-D.  I can add some of this discussion in the I-D if it
will help.

[MAP] The point of my diagram was that the only known use of any trunk group 
identifier is between the proxy and the gateway (interface "a" in the 
diagram). I don't see any application in which one proxy needs to pass a trunk group 
identity to another proxy. That was not in my diagram, nor is it explained in 
the draft as an application. Since the only need for an identifier is across 
interface "a", and, as you said, the Phone-context serves "little" purpose here, 
I propose it be deleted.

The only idea I could possibly come up with in which one proxy would send a 
trunk group identifier to another is when a trunk group directly connects two 
gateways which are controlled by those two proxies, and the signaling is 
directly between the proxies (via SIP). In this case, the two proxies should share a 
common trunk group identification scheme, so no additional information (e.g., 
"phone-context") would be needed to ensure that the identity is unique. In 
this case, P1 knows about the trunk groups at P2 because they are the same at 
both P1 and P2. Otherwise, P1 would have no reason to know about trunks group at 
P2.

In a message dated 1/21/2004 6:09:22 PM Romance Standard Time, [email-masked] 
writes:

[MAP] > The example in Section 6 uses "phone-context=+1-555-555". It is 
unknown 
> what this partial E.164 number could represent.

[VKG] Sorry; my mistake -- the number needs one more digit.  I'll fix it.

[MAP] That doesn't answer my question. No matter how many digits it has, if 
it looks like part of an E.164 number, I don't know how it relates to a trunk 
group.

Mike Pierce