When calling a phone number in another country, there is usually a prefix you have to dial to indicate that you're placing an international call; this varies by country. After that international dialling prefix, you must dial the international country code for the country you are calling, followed by the local number. This is a list of those country codes.
Note: The United States, Canada, and several Caribbean nations technically share the international calling code 1, with each state (or parts of states), province, territory, or island nation given its own three-digit "area code". The following list includes the area codes for such nations outside the US and Canada.