Technical Guide to Phone Numbers in Thailand

Quick Reference

• Country: Thailand
• Country Code: +66
• International Prefix: 00
• National Prefix: 0

Overview

This comprehensive guide offers an in-depth look at Thailand's telephone numbering system, focusing on number formats, dialing procedures, and regulatory considerations. It is essential for telecom professionals, developers, and anyone needing precise technical details on Thai phone numbers.

Numbering Plan Structure

General Number Structure

Thailand adheres to the ITU-T E.164 international numbering plan, an open numbering system. Thai phone numbers are structured as follows:

• Country Code: +66
• National (Significant) Number: 8 to 9 digits
• Subscriber Number: 7 to 8 digits

Number Components

Component	Description
Country Code	+66
National Prefix	0 (used for domestic dialing)
Subscriber Number	7 to 8 digits, varies by type (landline, mobile, etc.)
International Prefix	00 (used when dialing out of Thailand)

Number Formats

Landline Numbers

• Format: 0X-XXXX-XXXX
• Example: 02-123-4567
• Details: Landline numbers are 9 digits long, including the leading '0' for domestic dialing. The first digit after the '0' indicates the region.

Mobile Numbers

• Format: 0X-XXXX-XXXX
• Example: 081-234-5678
• Details: Mobile numbers are 10 digits long, including the leading '0'. The first two digits after '0' typically start with '06', '08', or '09'.

Toll-Free Numbers

• Format: 1800-XXX-XXX
• Example: 1800-123-456
• Details: Toll-free numbers in Thailand start with '1800' and are 10 digits long.

Premium Rate Numbers

• Format: 1900-XXX-XXX
• Example: 1900-123-456
• Details: Premium-rate numbers start with '1900' and are 10 digits long.

Regular Expressions

For developers and systems administrators, use the following regular expressions to validate Thai phone numbers:

• Landline: ^0[2-9]\d{7}$
• Mobile: ^0[689]\d{8}$
• Toll-Free: ^1800\d{6}$
• Premium Rate: ^1900\d{6}$

Dialing Procedures

Domestic Calls

• Landline to Landline: Dial the full 9-digit number, including the area code (e.g., 02-123-4567).
• Landline to Mobile: Dial the full 10-digit mobile number (e.g., 081-234-5678).
• Mobile to Mobile: Dial the full 10-digit number (e.g., 081-234-5678).

International Calls

• Outgoing: Dial 00 followed by the country code, area code (if applicable), and the subscriber number.
  • Example: To call a US number, dial 001-123-456-7890.
• Incoming: Dial +66 followed by the Thai number without the leading 0.
  • Example: To call a Thai mobile number from abroad, dial +66 81-234-5678.

Number Portability

Thailand has implemented Mobile Number Portability (MNP) since 2014, allowing users to retain their mobile numbers when switching between carriers. This service is regulated by the National Broadcasting and Telecommunications Commission (NBTC).

Major Telecom Operators and Number Ranges

Operator	Mobile Number Prefixes
AIS (Advanced Info Service)	08X, 09X, 06X
TrueMove H	08X, 09X, 06X
DTAC	08X, 09X, 06X

ITU-T Recommendations

Thailand adheres to the ITU-T E.164 standard, ensuring global interoperability of its numbering plan.

Number Allocation and Management

The National Broadcasting and Telecommunications Commission (NBTC) is responsible for the allocation and management of phone numbers in Thailand. The NBTC ensures compliance with ITU-T standards and regulates the telecommunications industry.

Technical Restrictions and Special Cases

• Golden Numbers: In Thailand, certain numbers considered "golden" or easy to remember may be auctioned or sold at a premium.
• Number Blocking: Number blocking is managed by the NBTC to prevent spam and misuse.

Technical Considerations for Developers

• Validation: Use the provided regular expressions to validate Thai phone numbers.
• Formatting: Ensure that phone numbers are correctly formatted for both domestic and international use.
• Portability: Account for number portability when designing systems that involve mobile numbers.

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References:

• NBTC Official Website
• ITU-T E.164 Recommendation
• NBTC Press Release (2014) - Number Portability Implementation
• NBTC Annual Report (2022) - Telecommunications Statistics