Out of service (some of the elevators labeled as not in use) is a special elevator mode designed to remove a specified elevator from service temporarily for maintenance, energy-saving, cleaning, or other reason.
How it works
Out of service mode is activated either by using a keyswitch or supervisory panel. By a keyswitch, it is activated using a keyswitch on the elevator hall/call station or a separate keyswitch panel. It is usually labelled as STOP/RUN, OOS, 0-I, etc. By a supervisory panel, it is activated using a keyswitch provided on the supervisory panel located on the elevator lobby or security room. When this mode is activated, the elevator is withdrawn from service and floor indicators on both inside and outside will display "OUT OF SERVICE" (for most elevators) or "PARK" (for some Otis and older Sigma elevators) sign, often a symbol.
Voice messages when the elevators being out of service
- "對唔住，本升降機停用 (Cantonese), 對不起，本升降機停用 (Putunghua), Sorry! Lift not in use. (English)" - elevators installed in the Hong Kong Mass Transit Railways (MTR) stations.