Phone Numbers From Around the World

What do you do with phone numbers?

I’ve used some different tricks to validate phone numbers in the North American format (999-999-9999), but I’ve learned that we also have invitees from Europe and other locales.  The problem I have, and I think it is a common problem, is that I need to be able to accept all possible phone number formats while attempting to validate the format used.  The goal of course is to minimize entry mistakes by the users.

I would love to hear your thoughts in the comments.