This doesn't work for phone numbers if you want to do something programmatically with them. In Germany it's for example common to include the international pref

This doesn't work for phone numbers if you want to do something programmatically with them. In Germany it's for example common to include the international prefix _and_ a trunk prefix like this in written phone numbers: +49 (0)30 23125 123 Your naive approach to just replace non-number characters would lead to an invalid number in such a case. Using libphonenumber you'd get a correctly normalized phone number while the user doesn't get bothered for inputting a technically invalid number: https://libphonenumber.appspot.com/phonenumberparser?number=%2B49+%280%2930+23125+123 https://libphonenumber.appspot.com/phonenumberparser?number=...