671 Area Code – Hagatna, Guam: Location, Time Zone & History

Chamorro culture on Guam blends indigenous traditions with American, Spanish, and Mexican influences layered on through centuries of colonial history, and English and Chamorro remain the island's two official languages, with Chamorros making up roughly a third of the population. It's against this backdrop that Guam's phone numbers carry area code 671, put into service on July 1, 1997 as the island joined the North American Numbering Plan, before that date, mainland callers had reached Guam only by dialing the ITU country code 671 as an international call.

Permissive dialing lasted a year, ending July 1, 1998, after which 671 became mandatory. More recently, on October 24, 2021, Guam adopted mandatory ten-digit local dialing ahead of the nationwide 988 lifeline rollout, even though the island has never needed an overlay. Beyond Hagåtña, the code reaches Dededo, Tamuning, Yigo, Mangilao, and Barrigada.

Guam's economy leans on tourism and on major U.S. Department of Defense installations, including Andersen Air Force Base and Naval Base Guam, alongside local retail and services. The 1950 Guam Organic Act established the island as an unincorporated organized U.S. territory and granted residents U.S. citizenship. As of 2026, area code remains Guam's only one, with no overlay in place.