If it's to help people identify where the phone number is from, then it's not a bad idea though the name of the country may be even clearer (how many flags do y

If it's to help people identify where the phone number is from, then it's not a bad idea though the name of the country may be even clearer (how many flags do you know?). E.g. Rebtel does this (to add a flag) in their app and website.