Calling French Guiana from the United States explained:

• 011 - US exit code; dial first for international calls made from the USA or Canada
• 594 - Country Code for French Guiana
• Phone Number (may not begin with 0) - 9 digits
• US to French Guiana international dialing format: 011 594 ??? ??? ???

How to dial to French Guiana cellular:

• dialing format for calls to a cell phone: 011 594 694 ??? ???

Phone Books:

• Pages Jaunes and Pages Blanches - French Yellow and White Pages respectively; to search Guiana phone numbers enter "Guyane" in the region (Ou) field