Re: Internationalization--Phone Number Writing Conventions

From: Markus Kuhn (
Date: Mon May 31 1999 - 18:18:32 EDT

Herman Ranes <> wrote:
> > I would suggest that, according to ISO standard, North American numbers
> > shall be written +1 XXX XXXXXXX or +1 XXXXXXXXXX depending on whether
> > seven- or ten-figure dialling is used locally.

"Hohberger, Clive P." replied on 1999-05-31 18:02 UTC:
> Herman,
> This is a brilliant example of an ISO "academic standard" It looks
> nice on paper, but doesn't meet peoples' real needs.
> [...] phone companies all over the world break their numbers
> in to smaller groups of digits with spaces, dashes etc.
> I guess it depends on "What's your objective?" Is it to have your
> phone number remembered or comply with an ISO standard?
[blablabla ...]

Even though I decided not to continue on this off-topic thread, the
level of ignorance has reached an emergency threshold where intervening
seems to become my moral duty. Therefore, please note the following
easily verifiable FACTS (as in opposite of "guesswork" and "rumours"):

A) There is no ISO standard for an international telephone number notation. *)

B) The relevant int. specification is ITU-T Recommentation E.123, which is
   available from the International Telecommunication Union web server on

   Downloading it will cost you 20 CHF (~12 USD) from your credit card
   unfortunately, but it is a standard that anyone involved with
   i18n and the design of web sites, business cards, letter heads, etc.
   should really have available as a reference. At least, it is still much
   cheaper than ISO documents of comparable length.

C) If you read the actual E.123 text, then you will notice that a lot of
   careful thought went into it and that none of your criticism applies.
   It has special rules for NA phone numbers (considering their different
   conventions) and it does take care of readability through inserting spaces.
   Your criticism is obviously completely based on guesswork and not on
   reading the standard. The penalty fee for this misbehaviour shall
   be 20 Swiss Francs. :-) Please read it.


P.S.: *) There is however an ISO standard for international postal
addresses, namely ISO 11180:1993, which is equally useful and worth
having a look at, especially if you are a US web site developer and want
to learn about why you probably frustrate the rest of the world with
your US-centric online address entry forms.

Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at,  WWW: <>

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