There are a number of free JavaScript phone number verification scripts, but the last time I checked (which was a long time ago), each script only checked phone numbers in a certain format. For example, one script only checks US phone numbers and another only checks US phone numbers. Is there a JavaScript script that can verify all international phone numbers?
I think you should narrow it down from 'all'. There are probably hundreds of phone number formats internationally. Focus on specifics and you'll get more luck.
I agree, I used to live i Bath btw. Anyway, you'd be better off using mySQL probably as the JS file would be huge too.