Area Code 53 – Chiang Mai/Chiang Rai/Lamphun/Mae Hong Son

Geographic Coverage and Administrative Jurisdiction

The +66 53 country-code prefix is a geographic National Destination Code (NDC) assigned to the upper northern region of Thailand. It serves the provinces of Chiang Mai, Chiang Rai, Lamphun, and Mae Hong Son. The code is administered under the National Broadcasting and Telecommunications Commission (NBTC) of Thailand and is allocated to fixed-line PSTN services within these provinces. Each province contains multiple local exchange areas, but the 53 prefix is used uniformly across the entire region, with subscriber numbers typically seven digits long, resulting in a complete national significant number (NSN) of nine digits (including the leading '0' when dialed domestically).

Primary Cities and Local Dialing

The principal city served is Chiang Mai, the largest metropolitan area in Northern Thailand, followed by Chiang Rai, Lamphun, and Mae Hong Son. Within these provinces, the prefix is used for both residential and business fixed lines. For local calls within the same exchange area, callers may dial only the seven-digit subscriber number. For calls from other provinces within Thailand, callers must dial the trunk prefix '0' followed by '53' and then the seven-digit subscriber number (e.g., 0 53 123 456).

International Dialing Format

For international callers, the correct format is the international access prefix (typically '00' or '+') followed by Thailand's country code '66', then the NDC '53' without the leading trunk '0', and finally the seven-digit subscriber number. For example, a Chiang Mai landline number 0 53 123 456 would be dialed as +66 53 123 456 from abroad. It is crucial to omit the leading '0' when dialing from outside Thailand.

Overlay and Numbering Considerations

As of the latest NBTC numbering plan, there is no overlay code for the 53 area; the region continues to use 53 exclusively for fixed-line services. However, mobile numbers in Thailand are non-geographic and begin with 6, 8, or 9, and are not tied to this area code. When calling a Chiang Mai mobile number from a fixed line in the 53 area, callers must dial the full mobile number including the trunk prefix '0'. Number portability is available for fixed-line services within Thailand, meaning a subscriber may retain their 53 number even if they move to a different exchange within the same province, but porting outside the 53 geographic region is not permitted.

Caller Instructions

For local callers within the 53 area: dial the seven-digit subscriber number directly for local calls. For domestic long-distance calls from other Thai provinces: dial 0 53 XXXXXXX. For international callers: dial your country's exit code, then 66, then 53, then the seven-digit number (e.g., +66 53 123 456). Ensure you do not include the leading '0' after the country code. This prefix is exclusively for fixed-line services; VoIP and mobile services may use different numbering schemes.