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    • New note by bobjonkman 4 January 2022
      According The Register's forum, this is the patch: "The current fix: Represent 2022-01-02 as 2021-12-33."https://forums.theregister.com/forum/all/2022/01/03/exchange_servery2k22_flaw/#c_4389861
    • Favorite 4 January 2022
      bobjonkman favorited something by lxo: what's most incredible about this date representation is that it was introduced after Y2K. it wouldn't have worked up to [19]99 think about it. someone implemented that after all the many years of preparation and patching decades-old systems for Y2K, knowing (or, worse, without realizing) that it had at most […]
    • bobjonkman repeated a notice by lxo 4 January 2022
      RT @lxo what's most incredible about this date representation is that it was introduced after Y2K. it wouldn't have worked up to [19]99 think about it. someone implemented that after all the many years of preparation and patching decades-old systems for Y2K, knowing (or, worse, without realizing) that it had at most a couple of […]
    • New note by bobjonkman 3 January 2022
      From what I can tell, they were using the decimal digits of the 32-bit number as a sort of BCD, with the base10 digits representing portions of the date. The example used is "the new date value of 2,201,010,001 is over the max value of 'long' int32 being 2,147,483,647". So, YY MMDDHHMM ? What an […]
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    • New note by bobjonkman 8 December 2021
      And, of course, Wikipedia knows everything: https://en.wikipedia.org/wiki/Foundation_series#Adaptations #Foundation
    • New note by bobjonkman 8 December 2021
      Happily, it's been about 50 years since I read the first three novels, and about 20 years since I started on the sequels (which never did finish, got about halfway through the third sequel book). So my foggy memories of the storyline in the original trilogy shouldn't detract from the TV series. I recall there […]
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      bobjonkman favorited something by clacke: @Bob Jonkman It is highly character-driven.It uses key characters, the Empire, the exile, Terminus, Psychohistory, two kingdoms instead of the Four Kingdoms and some echoes of half of the first book and fainter echoes from other parts of the series, while the main story maps roughly to half the first […]
    • bobjonkman repeated a notice by clacke 8 December 2021
      RT @clacke @Bob Jonkman It is highly character-driven. It uses key characters, the Empire, the exile, Terminus, Psychohistory, two kingdoms instead of the Four Kingdoms and some echoes of half of the first book and fainter echoes from other parts of the series, while the main story maps roughly to half the first book. It […]
    • New note by bobjonkman 7 December 2021
      Don't get me wrong, I think Foundation is one of the greatest SF stories ever written. And I hadn't heard there was a series, must find out when and where it airs... !SciFi @clacke

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 »

 
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