Abstract: An exchange having a display apparatus for displaying the states of a plurality of subscriber terminals accommodated therein. The display apparatus includes a display board having n indicator-keys, each for displaying the state of a subscriber terminal and an indication board having m indicator-keys, each for selectively indicating the states of n groups of subscriber terminals so that the states of a total of n.times.m subscriber terminals are displayed. Under control of the exchange, the display apparatus displays an incoming call and a recall terminated at an attendant console by lighting up the indicator-keys and flickering the indicator keys on and off, respectively. When an indicator-key which is displaying an incoming call or a recall is pressed, the subscriber terminal and the station line concerned are connected.