Businesses have been using telephone exchanges for decades. The concept is very similar to a public telephone exchange: the caller dials a number, and the call is routed using an internal system that’s private to the business itself. Colloquially, business exchanges are known as Private Branch eXchange (which is where ‘PBX’ comes from).
PBX systems initially ran on analogue lines and were manually operated by a human. They later ran on ISDN lines rented from BT and automation became more common. This kind of system has been used since the 1980s right through to the present day.
In the last decade, the hosted PBX has taken over from the PBX in many business settings. But why?