Subject: RE: [Sipping] Do Phones Have Dial Plans, or do Proxies map? was RE: [Sipping] Re: draft-schulzrinne-sipping-sos-04.txt

From: Adam Roach <[email-masked]>
Date: Thu, 9 Jan 2003 12:38:21 -0600

> - Translating abbreviations such as extensions and local-area 
> numbers to 
> fully-expanded, globally unique identifiers.

It's also interesting to note that many systems (e.g. PBXes)
include extensions that don't have an external representation.

For example, let's imaine a company that has a PBX with an
assigned range of +1-713-555-8xxx. They use 4-digit internal
dialling. Some extensions (e.g. 8123) can have an external
mapping (+1 713 555 8123). Others, like 3123, can't be reached
externally. They *can't* exist as fully-expanded, globally unique
identifiers.

So, how exactly do we address this? I see several options:

1) Allow "tel:" to include dialled digit strings, possibly
   with some parameter to indicate as much.

2) Create a new URI that is defined to carry dialled digits.

Both of these have their own rather obvious problems.
Can someone think of an alternate solution?

/a
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From: Paul Kyzivat <[email-masked]>
Date: Thu, 09 Jan 2003 14:00:21 -0500

I believe the current definition of tel: would want you to translate 
these numbers as follows:

   8123 => tel:+17135558123
   3123 => tel:3123;phone-context=+17135558

(Or use some other context, but this one should be legal for your case.)

This is no problem as long as the phone is presumed to have a full and 
complete dial plan that can turn ever dialed number into the proper 
valid tel: uri.

The problem comes if you want this task to be performed someplace else, 
like in a local outbound proxy. In that case, you need some way to 
convey the dialed digits to the proxy, where it can do its magic. See my 
earlier message for more on that.

	Paul