Area Codes (E.164 Calling) - Country Codes
E.164 country codes are country calling codes defined by the International Telecommunication Union (ITU). E.164 is recommendation which defines the international public telecommunication numbering plan.
The telephone numbering system has an international dialing prefix, such as “00″ or “011″, which is added before the country calling code. The need for this prefix is indicated with a “+”.