base unit; main telephone
Refers to the primary handset or base station in a system with extensions (子機). Common in home and office phone setups.
See also: 子機
If the base unit isn't charged, the cordless handsets won't work either.
When you buy a new phone, first connect the base unit to the telephone line.
Compound of 親 (oya, 'parent') and 機 (ki, 'device'), literally 'parent device'. The term follows a common pattern where 親 denotes the main or controlling unit in a set.