Anonymous
Because the police don't know if it's a false alarm.
?
That's what the alarm is for. If you don't want the police notified when your house is broken into, take out the alarm.
?
Because...when an alarm system is installed many of them have an option of being connected to the police department or not.
Silent alarms are usually connected with the police so the would-be thieves don't know they've been caught.