This gets into dial semantics vs. number format, which then becomes an element of user behavior. I don't know how user behavior is in a large number of other c

This gets into dial semantics vs. number format, which then becomes an element of user behavior. I don't know how user behavior is in a large number of other countries, but the U.S. I know typical reaction to "enter your full phone number" is area code + number, not 1 + area code + number.