The page is a list of country calling codes. These are area codes for telephone numbers.
Zone 1 - North American Numbering Plan Area
Places in the NANPA (North American Numbering Plan Area) have been given area codes as if they were all areas inside one country.
For more information please see nanpa.com
Zone 2 - Mostly Africa
Zone 3 - Europe
Zone 4 - Europe
Zone 5 - Mexico, Central and South America, West Indies
Zone 6 - South Pacific and Oceania
Zone 7 - Russia and its vicinity (former Soviet Union) 7 - Russia; Kazakhstan; Abkhazia (disputed with Georgia)