How to call Guam from the USA/Canada:

dial 1 + 671 + local phone number

Calling from another country?

The time in Guam is now 08:32:57am

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)

Phone Books:

The Guam Phone Book