Overview of Japan's Phone Number System
Japan's phone numbers are centrally managed by the Ministry of Internal Affairs and Communications (MIC) under Article 50 of the Telecommunications Business Act. Landline numbers are 10 digits including the area code, while mobile numbers are 11 digits. By examining the first few digits, you can determine whether a number belongs to a landline, mobile phone, toll-free line, or IP phone. Understanding this system helps you quickly assess the nature of incoming calls from unknown numbers.
The numbering system is divided into four main categories: landlines, mobile phones, IP phones, and special numbers. The MIC's Telecommunications Numbering Plan assigns number bands by purpose, with specific carriers and usage conditions defined for each band. Below, we explain the structure and practical points of each category.
Landline Number Structure
Area Code, Local Exchange Number, and Subscriber Number
Landline numbers consist of three elements: area code + local exchange number + subscriber number. Area codes range from 2 to 5 digits depending on the number of telephone subscribers in the region. Tokyo (03) and Osaka (06) have 2-digit codes, Yokohama (045) and Nagoya (052) have 3-digit codes, and Musashino (0422) has a 4-digit code. Shorter area codes mean longer local exchange numbers, always totaling exactly 10 digits. This fixed-length design allows switching equipment to determine routing based solely on digit count. Books on phone number systems offer more detail on the numbering plan.
Identifying Regions by Area Code
The digit following the leading 0 indicates the general region: 01 for Hokkaido, 02 for Tohoku/North Kanto, 03 for Tokyo's 23 wards, 04 for South Kanto/Koshinetsu, 05 for Chubu/Tokai, 06 for Osaka City, 07 for Kinki, 08 for Chugoku/Shikoku, and 09 for Kyushu/Okinawa. This pattern was established during the 1960s nationwide automatic dialing plan and has been maintained for over half a century. See How to Look Up Area Codes and Identify Regions for details.
Landline Digit Patterns
- 2-digit area codes: 03 (Tokyo 23 wards), 06 (Osaka City) and other major cities. 4-digit local exchange + 4-digit subscriber number
- 3-digit area codes: 011 (Sapporo), 045 (Yokohama), 052 (Nagoya), etc. 3-digit local exchange + 4-digit subscriber number
- 4-digit area codes: 0422 (Musashino), 0798 (Nishinomiya), etc. 2-digit local exchange + 4-digit subscriber number
- 5-digit area codes: 04992 (Hachijojima) and other remote islands. 1-digit local exchange + 4-digit subscriber number
Mobile Phone Number Structure
Mobile phone numbers are 11 digits starting with 090, 080, or 070. Unlike landlines, they are not tied to any geographic region and are used nationwide. Since the introduction of MNP (Number Portability) in 2006, it is no longer possible to identify the carrier from the first three digits.
History of Each Number Band
The 090 band was first assigned during the 1999 transition to 11-digit numbers. As subscribers grew, the 080 band was added in 2002, and in 2013 the 070 band - previously reserved for PHS - was opened to mobile phones as well. According to MIC statistics, the total allocation across 090, 080, and 070 reached approximately 190 million numbers as of March 2024. The potential opening of the 060 band is also under consideration. Recommended landline phones can help you compare communication devices.
IP Phone Number System
IP phones (VoIP) use 11-digit numbers starting with 050. These services carry voice calls over the internet and are typically cheaper than traditional landlines. However, 050 numbers may not support emergency calls (110/119), as the MIC does not mandate emergency call capability for 050 IP phone services.
In recent years, IP phone services like NTT's Hikari Denwa (fiber optic phone) have become widespread, offering numbers with traditional area codes (0AB-J numbers). These are technically IP phones but use the same numbering system as conventional landlines, providing greater social credibility. Following the completion of the PSTN to IP network migration in January 2025, all landline calls are now technically routed over IP infrastructure.
Special Number Bands
- 050: IP phone. Internet-based telephone service
- 0120: Free Dial. Toll-free number where the receiver pays call charges
- 0800: Free Call. A toll-free service similar to 0120
- 0570: Navi Dial. Nationwide flat-rate number where the caller pays
- 0990: Premium-rate information service number. Information fees charged on top of call charges
- 110, 119, 118: Emergency numbers. For police, fire/ambulance, and Japan Coast Guard
Future Outlook for the Numbering System
With the spread of smartphones and the growth of IoT devices, demand for phone numbers is expected to continue rising. The MIC's Information and Communications Council is considering the opening of the 060 band for mobile phones (adding approximately 90 million numbers) and expanding the 020 band for M2M (machine-to-machine) communications. The 020 band operates with 14-digit numbers, providing a space of roughly 80 billion numbers to accommodate the rapid growth of IoT devices such as vending machines and smart meters.
Japan's Phone Numbers in an International Context
Japan's phone number system complies with the E.164 recommendation established by the ITU. E.164 defines the international format for phone numbers, uniquely identifying any number worldwide through a combination of country code + national number. Japan's country code is +81, and converting to international format requires dropping the leading 0 (trunk prefix) and replacing it with +81. See Guide to Japan's Country Code +81 for details.
For example, a Tokyo landline number 03-1234-5678 becomes +81-3-1234-5678 in international format. A mobile number 090-1234-5678 becomes +81-90-1234-5678. Understanding this conversion rule is essential when communicating internationally or registering numbers with global services.
Detailed Number Band Classification
Japanese phone numbers are clearly classified by their leading digits. Knowing this classification lets you instantly identify the type of incoming call.
0A-0J Numbers (Landlines)
Landline numbers beginning with area codes. The digit after 0 (1-9) indicates the general region. The subscriber number is always 4 digits, with the area code and local exchange number totaling 6 digits.
020 Numbers (M2M Communications)
A number band dedicated to IoT devices and M2M (Machine to Machine) communications. Operating with 14 digits, it provides a space of roughly 80 billion numbers, assigned to vending machines, smart meters, and vehicle telematics devices.
0AB0 Numbers (Special Services)
Number bands assigned to special services such as 0120 (Free Dial), 0570 (Navi Dial), and 0800 (Free Call). These numbers are not tied to any region and are used nationwide.
Phone Numbers and Personal Information
Phone numbers may qualify as "personal information" under Japan's Act on the Protection of Personal Information. The 2022 amendment clarified that even a phone number alone can be treated as "personal-related information" requiring careful handling. Since a phone number combined with a name or address can identify an individual, businesses collecting customer phone numbers must clearly state the purpose of use and implement appropriate security measures.
Additionally, if your phone number is registered with social media or web services, there is a risk of being identified through reverse lookups. For those who value privacy, consider using different numbers for different services or using a 050 IP phone number as a secondary number. It is also wise to familiarize yourself with what to do if your phone number is exposed in a data breach.
Numbering Plan Management and the Role of the MIC
Japan's phone numbering plan is developed and managed by the Ministry of Internal Affairs and Communications (MIC). Under the Telecommunications Business Act, number blocks (typically in units of 10,000) are allocated to carriers. Allocation status is published on the MIC's "Telecommunications Number Designation Status" page, where you can check which number bands are assigned to which carriers. To prevent number exhaustion, unused numbers are periodically reclaimed and redistributed.
Numbering plan revisions are discussed by the Information and Communications Council, adapting flexibly to social conditions and technological changes. Recent key topics include expanding the 020 band for the surge in IoT devices and opening the 060 band in anticipation of mobile number exhaustion. A systematic understanding of the numbering system serves as a foundation for choosing communication services and dealing with unknown numbers.