... Remote controller 3) Button: 1-key button, 2-key button, 3-key button (choose one or more) 4) Signal enhancer (optional) 5) Button stand (optional) System ... can transmit 2 request messages (service and cancel), 3-button requester can transmit 3 request messages (service, bill and ... cancel). And each button can be defined as needed such as call, drink, cashier ...