Guam +1 (671)
Number Format
Area Code: 3 digits
Subscriber Number: 7 digits
Trunk Prefix: 1
International Prefix: 011
1 July 1997 - switch from +671 to +1 671
Guam originally used country code +671. It began to move under the North American Numbering Plan (NANP) on 1 July 1997 with the introduction of +1 671.
A permissive dialling period continued until 1 July 1998, after which +671 was discontinued and +1 671 became mandatory.
See: Guam Telephone Authority announcement (via ITU, 21 April 1997).
Other Information
Carrier is Guam Telephone Authority (website may have limited details).
See United States Pacific Islands section.