Japanese landline numbers consist of 10 digits: an area code, a city code, and a subscriber number. Area codes start with 0 and are 2 to 5 digits long. Major cities with many subscribers have shorter codes (03 for Tokyo, 06 for Osaka), which leaves more digits for the city code, so the combined length stays the same nationwide.

Because area codes map to regions, the first few digits of an unknown number can tell you roughly where a call comes from. In contrast, mobile numbers (070, 080, 090), IP phone numbers (050), and toll-free numbers (0120, 0800) are not tied to any region. Area code assignments are managed by the Ministry of Internal Affairs and Communications under the national numbering plan and can change as regional circumstances evolve.

This page organizes number ranges by line type. Select a range to see the phone numbers registered in it and the spam call reports for each number. If you receive a call from an unfamiliar area code, we recommend checking the caller before calling back.