What the international code for French Guiana to call? Dial code number to open phone call in French Guiana is ( 00594 ) or ( +594 ) in order to make international phone calls between French Guiana and all countries of the world to unlock phone with more additional details and informations about French Guiana country whereby each country is distinguished by a special telephone number, where the caller write the French Guiana dial area code to opening sim card telephone line mobile or landline then the phone number.