Calling Guam from the United States explained:
- 1 - Country Code for Guam
- 671 - area code within the NANP
- local phone number - 7 digits
- US to Guam international dialing format: 1 + 671 + ??? ????
- this US territory is part of the North American Numbering Plan - NANP (calling it works like a US state to state call)