Understanding Phone Numbers in Japan

Quick Reference Guide

• Country: Japan
• Country Code: +81
• International Prefix: 010
• National Prefix: 0

Overview of Japan's Telephone Numbering Plan

Japan's telephone numbering system, regulated by the Ministry of Internal Affairs and Communications (MIC), follows ITU-T E.164 standards. This guide provides essential insights into number formats, dialing procedures, and regulatory frameworks, ideal for telecom professionals, developers, and system administrators.

Number Formats in Japan

General Number Structure

• Format: +81 [Area Code] [Subscriber Number]
• Length: Typically 10 digits (excluding the country code)

Geographic Numbers (Landlines)

Geographic numbers are region-specific, with area codes ranging from 1 to 5 digits.

• Format: 0[Area Code][Subscriber Number]
• Example: 03-1234-5678 (Tokyo), 0742-123-456 (Nara)

Mobile Numbers

Mobile numbers are distinguished by prefixes 070, 080, and 090.

• Format: 0[7-9]0[Subscriber Number]
• Example: 090-1234-5678

Toll-Free Numbers

Toll-free numbers have specific prefixes, allowing free calls for the caller.

• Format: 0120[Subscriber Number]
• Example: 0120-123-456

Premium Rate Numbers

Used for services with higher charges, identified by the prefix 0990.

• Format: 0990[Subscriber Number]
• Example: 0990-123456

Special Service Numbers

• Emergency Services: 110 (Police), 119 (Fire and Ambulance)
• Directory Assistance: 104
• Disaster Relief: 171

Dialing Procedures

Domestic Calls

• Landline to Landline: Dial the full number, including the area code.
• Landline to Mobile: Use the full mobile number with the prefix.
• Mobile to Mobile: Simply dial the full mobile number.

International Calls

• Outgoing: Dial 010, followed by the country code, area code, and subscriber number.
• Incoming: Dial +81, followed by the area code (without the leading 0) and subscriber number.

Number Portability

Japan supports number portability for both fixed-line and mobile numbers, allowing users to retain their numbers when switching operators.

Major Telecom Operators

• NTT Docomo: Handles mobile numbers with prefixes 090, 080, and 070.
• KDDI (au): Manages similar mobile prefixes.
• SoftBank: Covers a significant share of mobile numbers.
• NTT East/West: Manages most geographic numbers.

Technical Considerations for Developers

• Validation: Use regex patterns to ensure correct phone number formats.
• Normalization: Strip non-numeric characters and format numbers according to international standards.
• Portability Checks: Implement APIs for number portability verification.

Regex Patterns for Number Validation

• Geographic Numbers:
  ^(0\d{1,4})-(\d{1,4})-(\d{4})$
  

• Mobile Numbers:
  ^(0[7-9]0)-(\d{4})-(\d{4})$
  

• Toll-Free Numbers:
  ^(0120|0800)-(\d{3})-(\d{3,4})$
  

• Premium Rate Numbers:
  ^(0990)-(\d{6})$