For north american phone numbers, (999) 999-9999 works pretty well for an input mask.
However, I can't find a good example that will handle non-north american numbers. I know that the number of digits can vary, so other than restricting it to digits only, is there a good example anywhere?
There is no generic mask, really: There are too many combinations.
The only thing that is fixed is the international country code, usually prefixed by +
.
According to the Wikipedia Article on telephone numbering plans, most countries conform with the E.164 numbering plan.
If I read E.164 correctly, you can safely make the following assumptions:
Country code: 1-3 digits
Network / Area code and Number: Up to 19 digits
I would ask for the country code, and have the "area code + number" field as a 19-digit input.