How can I format, parse, and validate telephone numbers according to locale?

Brian Ewins

You may want to look at the international standard for telephone numbering. This is the ITU (International Telecommunication Union) publication no. E.164, The international public telecommunication numbering plan.

It's 20 swiss francs, but the ITU used to allow you two document downloads when you register, so you can probably get hold of one (PDF) copy for free.