How to typeset telephone numbers properly?

There is the telprint package, but it is designed for the German format for telephone numbers.

Examples from the manual:

\telprint{0761/12345} ==> 07\,61/1\,23\,45
\telprint{01234/567-89} ==> 0\,12\,34/5\,67\leavevmode\hbox{-}89
\telprint{+49 (6221) 297} ==> +49~(62\,21)~2\,97

I think that in these cases is good to refer to some standards, such as those of the International Telecommunication Union: E.123 : Notation for national and international telephone numbers, e-mail addresses and web addresses. (Section 2 Notation for National and International Telephone Numbers, of the English version).

The European Union recommendations can be found here.

• Indicate the number in its international form.

• Prefix the international dialling code with a plus sign ‘+’ (no following space) indicating the need to add the prefix for international calls.

• After the international dialling code and a space, the complete number, including the regional code if there is one, is presented in a single block:

             +33 140633900

• An extension number is separated from the main number by a hyphen. Do not pair off the digits of an extension number. They appear in a single block:

             +32 222020-43657

It goes without saying that this is the worst method possible to print a number in order to scan and remember it.