RE: MMUSIC+PINT joint WG Last Call draft-antti-telephony-url-09.txt

[Dean Willis <[e-mail]>]

Lawrence made a key point for me in his discussion of
draft-antti-telephony-url-09.txt.

The draft, as it exists, has no clearly delineated mechanism for supporting
private context. Some of the folks in the office believe this to be a "show
stopper" on acceptance of the current draft. Private context seems to me to
be a key enabler for virtual private dial neworks (VPDNS), or private
numbering plans, and that's a very important application.

In fact, I see two different sorts of private context.

For routing functions in GSTN, we use the dialed-digit string and Nature of
Address (NOA) and Numbering Plan Indicator (NPI) values from ISUP. NOA
includes scopes like "global", "local", and "private", and NPI provides a
code point for differentiating between numbering plans at the same scope
level. To represent this in a URL, we need to have some equivalent function.

At the raw switch level there is no understanding of numbering plans, etc.
All the switches can do is outpulse a dialed digit string onto a trunk which
is part of a trunk group (TG). That is, dialed 8227891 on trunk group 1
might go someplace very different than dialed 8227891 on trunk group 2 of a
given switch. To terminate a call from IP into a switch (without making
another IN call), we need to be able to specify the correct trunk group to
use. It would be nice to be able to represent this in the URL as well.

I had initially considered proposing to use the future-extension syntax of
draft-antti-telephony-url-09.txt to provide for NOA, NPI, and TG. It would
be easy enough to add ";NOA=1;NPI=2345" or ";TG=23456" to a TEL URL this
way.

Perhaps the PINT "private context" notation would be equally useful.

Of course, it would nice if the representation of private context for NOA,
NPI, and TG were standardized, as this would make buying gateways much
easier . . .

Thoughts?

--
Dean Willis