I’ve not used this before, but I’m working on a page where it would definitely be useful. I anticipate most callers will come from within the same country, but a significant number will be international. If I’ve understood correctly, I can insert the telephone number in the international format, and the user-agent should be able to determine whether or not it is local. Is it safe to do this, or might it cause problems for the majority of users? I’ve tried searching, but found surprisingly little information.
I’m not a phone user, so this whole area is a mystery to me.