It consists of a smoke detector manual call point and an Electronic Hooter. It is placed in the lift, stairway and lobby of every floor. The smoke detector call point and hooters are connected to the Main Control Panel on the ground floor, which is watched by the security people. In the event of fire, the glass of the manual call point is broken.

Thus the Hooter on that floor will be activated and in turn, the main control panel will give a flashing LED display and sound an audible alarm.
This is statutory requirement for obtaining N.O.C. from the Fire Brigade.