Your comment about phone number validation is spot on. I have had to resort to typing in random numbers to get past a screen that insisted on a US format number. In all probability if the organisation was going to phone me it would be a real person doing the dialing, so there is no need to have any form of validation. I have yet to see a validation routine that can handle:
"(+44)207 123 4567 ext. 1234 during UK office hours only, or (+44) 7901 2345 6789
the rest of the time", but experienced phone users would have no problem.