As intelligent as it can be, once the main panel is alerted that there is an intrusion it cannot distinguish whether it is you entering the house or an intruder. Therefore the main panel will wait for verification from the owner before it sounds the alarm. This verification is given to the system in the form of a unique code which is entered into the keypad so that the main panel recognizes that it is the owner of the premises that has entered, and not an intruder. The main panel allows a brief waiting period to allow the owner to input the code on the keypad. If the waiting time is exceeded and no code is inputted, the main panel will give a signal to the sounders and dialler to turn on, since it assumes that there is an unauthorized intruder. The waiting time is variable and is set at installation stage.
There can also be more than one keypad in a building. This enables one to switch on and off the alarm from more than one location, and can be useful in houses with a separate garage entry. Some alarms also have the facility to be set on and off using a remote, without the need to remember and input any code. The keypad also allows control over several other functions of the alarm system.