A business phone is a commercial telephone system for offices and stores. Unlike home phones, it consists of a main unit (controller) and multiple dedicated handsets, supporting extension calls, shared outside lines, hold/transfer, and incoming call distribution.
The core concept is sharing a few outside lines across many handsets. For example, 3 outside lines shared among 10 handsets allow 3 simultaneous external calls while the rest handle internal calls - far cheaper than individual lines for each desk.
Key features include hold transfer (hold and redirect to another person), park hold (place a call on a shared hold button accessible from any handset), pickup (answer another desk's ringing phone), and absence forwarding (auto-redirect when unavailable).
Traditional systems cost hundreds of thousands to millions of yen for hardware and installation. Cloud PBX now replaces physical hardware with cloud services, using smartphones and PCs as extensions - dramatically reducing costs and enabling remote work.