The call button is for guest .

The signal receiver is for waiter or waitress .

This wireless transmitter bells are typically placed on or attached to each table.When a guest wants his or her server, he/she presses the button of a service bell, which sends a signal to the central receiver. The Receiver displays numbers, usually table numbers, which the guest has sent, and flashes briefly and beep sounds to indicate that a new call has been received.