What the international code for United States of America to call? Dial code number to open phone call in United States of America is ( 001 ) or ( +1 ) in order to make international phone calls between United States of America and all countries of the world to unlock phone with more additional details and informations about United States of America country whereby each country is distinguished by a special telephone number, where the caller write the United States of America dial area code to opening sim card telephone line mobile or landline then the phone number.