This Blog Is Not For Reading

A blog, just like any blog, only more so

  • Subscribe

  • Categories

  • RSS Bob Jonkman’s Microblog

    • New note by bobjonkman 19 January 2018
      Are there no data !privacy standards in India? Is there a government privacy commissioner?
    • bobjonkman repeated a notice by arunisaac 19 January 2018
      RT @arunisaac IISc is asking students' for Aadhaar again. This time, it is for NAD (National Academic Depository) registration. Guess what, they have shared a public spreadsheet with 4000 students' details (name, dept, gender, caste/category, etc.), with a blank column for Aadhaar. They expect people to enter their Aadhaar IDs in this public spreadsheet! Such […]
    • Favorite 19 January 2018
      bobjonkman favorited something by chr: - javascript is also increasingly being abused by companies that recognize its universality to deliver javascript programs that enable tracking and abuse of my computing environment - this behavior is being enabled by websites that should be able to work without javascript nonetheless requiring js and failing silently without italso […]
    • New note by bobjonkman 18 January 2018
      I've been a SysAdmin for about 30 years, I've installed OSes from the days when you had to format a hard drive with debug G=C800:5, I've installed, destroyed, repaired and recovered Netware, Windows and Linux systems. But flashing a phone or tablet scares the willies out of me.
    • Favorite 18 January 2018
      bobjonkman favorited something by art: I'm experimenting with #Searx as my main search engine. I love #duckduckgo but I think I need something more decentralized.
    • Favorite 18 January 2018
      bobjonkman favorited something by art: Linkedin is dumb.
    • New note by bobjonkman 18 January 2018
      Hi @EineBiene: The groups I created are all at http://sn.jonkman.ca/groups/ There are currently no plans to move them; my https://gs.jonkman.ca/ instance is too flakey right now -- I can't subscribe to my own groups, for example. Unfortunately, I believe there are also other !GNUsocial users who cannot subscribe to groups on sn.jonkman.ca, so something does […]
    • New note by bobjonkman 18 January 2018
      Hi @EineBiene: The groups I created are all at http://sn.jonkman.ca/groups/ There are currently no plans to move them; my https://gs.jonkman.ca/ instance is too flakey right now -- I can't subscribe to my own groups, for example. Unfortunately, I believe there are also other !GNUsocial users who cannot subscribe to groups on sn.jonkman.ca, so something does […]
    • New note by bobjonkman 18 January 2018
      Lovely eggs, abominable website. #ProTip: Don't use horizontal scrolling.
    • Favorite 18 January 2018
      bobjonkman favorited something by pabo: @bobjonkman Couldn't agree more with @lnxw48a1 . All this site has to do is share my resume and any other data I provided that might interest potential employers.Instead, it's hiding increasingly more info behind an authentication wall.[1]And while that sounds bad and weird, but does have some merit (deny anonymous […]

Archive for March, 2010

Telephone Number Format Standards

Posted by Bob Jonkman on 20th March 2010

Telephone Dial

Standardized Telephone Number formats work even on old phones!

There are many different address books and directories online, and there are almost just as many different ways they store telephone numbers. I guess most people don’t realize that there are actually standards for representing phone numbers. A little bit of standardization would go a long way towards interoperability.

The standard for phone number formatting is set by the International Telecommunication Union in [E.123] and [E.164] (see the references below). The standards documents are available for a fee from the ITU [available at no charge since 2010 –Bob.] . A summary is available in the Google (UseNet) discussion group, titled Need ITU-T E.123 summary.

In short, a North American telephone number should look like:

+C-AAA-PPP-NNNN;ext=xxxx

  • “+” shows where the dialing prefix goes. This is one of either the International Direct Dialing (IDD) prefix (for Canada this is “011” for overseas dialing) or the National Direct Dialing (NDD) prefix (“1” for calls within North America, omitted for toll-free calls),
  • “C” is the Country Code (North America’s CC is “1”, and it is omitted for dialing within North America),
  • “AAA” is the area code (always required for dialing in Kitchener, Toronto, and other jurisdictions),
  • “PPP” is the Exchange (or Private Branch Exchange “PBX”; look in the phone book to see which exchanges are supported),
  • “NNNN” is the local portion of the number,
  • “;ext=” optionally identifies the next portion as an extension and “xxxx” are the digits for that extension. This syntax is usable in URIs and e-mail.

Note that the sequence “AAA-PPP-NNNN” is called a “local number” and “+C-AAA-PPP-NNNN” is called a “global number”. The “-” (hyphen) is a visual separator, as are “.” (period) , “(” (left bracket) and “)” (right bracket), which dialing applications should ignore.

I’m mostly interested in making phone number formats in e-mail addressbooks compliant with e-mail standards. The document that covers this is the IETF’s [RFC3191], "Minimal GSTN address format in Internet Mail" . The requirement is that GSTN (Global Switched Telephone Network) numbers use the global-number syntax (“+C-AAA-PPP-NNNN”).

Global-number GSTN numbers can be used for other purposes as well, such as Web page URIs. See [RFC3966], "The tel URI for Telephone Numbers". This document re-iterates that:

5.1.4.
Global Numbers Globally unique numbers are identified by the leading “+” character. Global numbers MUST be composed with the country (CC) and national (NSN) numbers as specified in E.123 [E.123] and E.164 [E.164]. Globally unique numbers are unambiguous everywhere in the world and SHOULD be used.
5.1.5.

Local Numbers Local numbers are unique only within a certain geographical area or a certain part of the telephone network, e.g., a private branch exchange (PBX), a state or province, a particular local exchange carrier, or a particular country. URIs with local phone numbers should only appear in environments where all local entities can successfully set up the call by passing the number to the dialling software. Digits needed for accessing an outside line, for example, are not included in local numbers. Local numbers SHOULD NOT be used unless there is no way to represent the number as a global number.

Local numbers SHOULD NOT be used for several reasons. Local numbers require that the originator and recipient are configured appropriately so that they can insert and recognize the correct context descriptors. Since there is no algorithm to pick the same descriptor independently, labelling numbers with their context increases the chances of misconfiguration so that valid identifiers are rejected by mistake. The algorithm to select descriptors was chosen so that accidental collisions would be rare, but they cannot be ruled out.

If you work at a company that does work with organizations and staff members outside of the context of your area code (ie. internationally) be sure to standardize your directory on global-number syntax.

–Bob.

Need a consultant? Bob Jonkman can be reached by telephone at +1-519-635-9413

References:

Image: Telephone Dial by Leo Reynolds, used under Creative Commons v2.0 BY-NC-SA.

Posted in code, smtp, telephone, valid html | 4 Comments »

 
Better Tag Cloud