Area code 671 serves the U.S. territory of Guam, located in the western Pacific Ocean. It was incorporated into the North American Numbering Plan in 1997, replacing the country code +671 and aligning Guam with U.S. dialing patterns. The area code covers the entire island, including the capital Hagåtña and major cities like Dededo and Tamuning. Guam’s 671 is unique as one of the few area codes outside the continental U.S., used for both local and military communications. Ten-digit dialing is required, but calls to Guam are treated as domestic from the U.S. mainland. The code plays a vital role in connecting Guam’s residents and its strategic military presence to the broader American telecom network.