Subject: [VCARDDAV] Making TEL value stricter

From: Simon Perreault <[email-masked]>
Date: Mon, 17 Mar 2008 14:11:14 -0400

Hi all,

I did some research on telephone number standards and it seems like this is a 
tar pit, much like address formats.

First, I'd like to make TEL follow E.123, of which you can download a PDF at 
http://www.itu.int/rec/T-REC-E.123-200102-I/e. It defines two formats: 
national and international. Here are two examples:

National: (555) 555 5555
International: +1 555 555 5555

We can differentiate between the two by checking for the presence of the plus 
sign. The only meaning given to the digit groups is that the one following 
the plus sign is the international prefix, and the one in parentheses is the 
trunk code. The meaning, size, and number of the other digit groups is not 
defined. To indicate an extension number, you append " ext. 5555" to either 
of the above.

Here's the proposed ABNF:

   phone-number = phone-prefix 1*(SP 1*DIGIT) [phone-ext]

   phone-prefix = "+" 1*DIGIT / "(" 1*DIGIT ")"

   phone-ext = SP "ext." SP 1*DIGIT

E.163 doesn't actually specify digits. Instead, it uses the concept of 
a "diallable symbol", which may be a digit, a letter, or anything else. I 
intentionally used only digits.

Comments on this first step? Does it completely fulfill the need for 
strictness or should we invent a new property with components?
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From: Simon Perreault <[email-masked]>
Date: Mon, 17 Mar 2008 14:34:47 -0400

On Monday 17 March 2008 14:11:14 Simon Perreault wrote:
> First, I'd like to make TEL follow E.123

*sigh* I just found out about RFC 3966. It would be better to use it I think.
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From: Lisa Dusseault <[email-masked]>
Date: Mon, 17 Mar 2008 11:37:48 -0700

I've had some discussions with Cullen Jennings about standardizing  
telephone number formats around the TEL URI.  As you say, this is a  
tarpit, and it's better that we solve this in a smaller number of  
places rather than deal with everything in many places.

The Tel URI is extensible in case it doesn't start out with the right  
features.  (E.g. I recently had a discussion about how to add a  
"subject" parameter in an extension to the URI, so that SMS msgs  
triggered by the Tel URI could have a subject.)

That said, I'm not sure a URI is right for this particular need.   
Just wanted to throw this in.

Thanks,
Lisa

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From: Cyrus Daboo <[email-masked]>
Date: Mon, 17 Mar 2008 14:40:14 -0400

Hi Simon,

> *sigh* I just found out about RFC 3966. It would be better to use it I

Are you suggesting we allow VALUE=URI on TEL: properties and then use a 
tel: URL as the actual value?

-- 
Cyrus Daboo

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From: Simon Perreault <[email-masked]>
Date: Mon, 17 Mar 2008 15:10:38 -0400

> tel: URL as the actual value?

Yes, that was the implication. But it would be sooooooo ugly!

tel:tel:911