The country code 66 is used to identify Thailand as the destination country of a call made from another country. The dialing code 66 is usually accompanied by city or area codes to direct international callers towards the specific region to which they are calling.
Area codes within Thailand are tied to a geographic numbering convention: a single digit associated with Bangkok and its neighboring regions, while two digits identify regions and provinces outside of Bangkok. Area codes in Thailand follows geographical province borders, and a single area code is often shared by different provinces. The Ministry of Information and Communication Technology of Thailand regulates telephone numbers within the country.