noun
local exchange number; local exchange prefix
Telecommunications term for the part of a phone number that identifies the local exchange within an area code.
電話番号は市外局番、市内局番、加入者番号から構成されます。
A phone number consists of an area code, a local exchange number, and a subscriber number.
Compound of 市内 (within the city) + 局番 (exchange number).