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    • New note by bobjonkman 29 November 2020
      Bread machines are great. I haven't bought a loaf of bread in about three years. If #sonTwo's bread machine has custom settings, I recommend 20 min knead time, changing the rise times (1hr, 1.5hrs, 1.5hrs) and at least 60-70 min bake time. A good recipe is 1 cup water, 2.5 cups all-purpose flour, 2 tbsp […]
    • bobjonkman repeated a notice by lnxw48a1 29 November 2020
      RT @lnxw48a1 #sonTwo texted to tell me that his in-laws bought them a bread machine. Me: Oh, cool! I was thinking the same thing, but it's beyond my current budget. They can sometimes be competitive, but I'm more of *good, you're helping take care of our kids and grandkids*
    • New note by bobjonkman 28 November 2020
      I'm near the Great Lakes (about an hour's drive from either Lake Ontario or Lake Huron, depending whether I go South or West). It was 5C for most of the day, about 40F for your USians. Apparently that's normal for this time of year...
    • bobjonkman repeated a notice by lnxw48a1 28 November 2020
      RT @lnxw48a1 About halfway through today's #YoCo ( #yogurt and #coffee ). Indoor temperature is 60°F, outdoor temperature is 30°F. Outdoor cats' water dish has about 0.5in / 1cm of ice on top. Very glad I'm not near the Great Lakes right now.
    • Favorite 24 November 2020
      bobjonkman favorited something by lnxw48a1: @vegos I agree. To most organizations, their primary concern is reach. So they congregate on big #corpocentric #socnets, even when the central corporation running things is actively hostile to their point of view. Then they're butthurt when their accounts are shadowbanned. Years ago, I tried to persuade some local Black […]
    • bobjonkman repeated a notice by lnxw48a1 24 November 2020
      RT @lnxw48a1 @vegos I agree. To most organizations, their primary concern is reach. So they congregate on big #corpocentric #socnets, even when the central corporation running things is actively hostile to their point of view. Then they're butthurt when their accounts are shadowbanned. Years ago, I tried to persuade some local Black churches and ethic-focused […]
    • bobjonkman repeated a notice by lnxw48a1 24 November 2020
      RT @lnxw48a1 https://techcrunch.com/2020/11/24/australia-spy-agencies-covid-19-app-data/ [techcrunch com] #Australia spy agencies caught collecting #COVID-19 app data #surveillance Source: https://mastodon.social/@glynmoody/105266051824700682
    • New note by bobjonkman 3 October 2020
      There's also Megablocks, the precursor to Duplo. And there are also Micro Megablocks, the same size as LEGO. The kits for Micro Megablocks were much better than the LEGO kits, making slightly larger models but using only standard bricks. The LEGO models were smaller, depending on many custom pieces specific to the kit, which were […]
    • Favorite 3 October 2020
      bobjonkman favorited something by clacke: Not only are Duplo blocks *like* Lego blocks, they *are* Lego blocks, and I don't just mean that Duplo is a Lego brand and produced in the same factory, the two systems are actually compatible.A Lego 2x2 block fits and sticks to the underside of a Duplo block, and the […]
    • bobjonkman repeated a notice by clacke 3 October 2020
      RT @clacke Not only are Duplo blocks *like* Lego blocks, they *are* Lego blocks, and I don't just mean that Duplo is a Lego brand and produced in the same factory, the two systems are actually compatible. A Lego 2x2 block fits and sticks to the underside of a Duplo block, and the nob on […]

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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