We use libphonenumber from Google to do just that. Have to stay on top of the latest library version, though, to avoid pissing off customers when their country

We use libphonenumber from Google to do just that. Have to stay on top of the latest library version, though, to avoid pissing off customers when their country's phone format changes, which happens surprisingly often. I subscribed to the ITU-T newsletter for a while, and there are phone number format changes somewhere in the world every month. Kind of amazing.