Country Code is a free website that lists all country calling codes. The information is also widely available online, in list form and for each specific country.
Country Code lists each country's calling code, ISO country code, population, area and GDP. The ISO country code is a 2- or 3-letter code used by the International Organization for Standardization code to identify a country for a variety of reasons; these codes are also often used as web domain suffixes.
To call an international number, first the caller must dial the International Direct Dialing number, which varies from country to country. In the United States, this number is 011. Then, the caller can enter the country's calling code, followed by the phone number he or she is trying to reach. It is important to note that the phone number may have an area code for the specific state or province that is being called.
The world is divided into nine zones for the purpose of assigning calling codes. North America makes up Zone 1, and the calling code for both the United States and Canada is 1. Zones 3 and 4 are in Europe, while Asia is split between Zones 6, 8 and 9.