Monitored alarms are promoted and sold by professional alarm companies. The homeowner is contracted to pay a monthly fee, and often receives a discount on the installation and cost of the equipment. In the mid-2000s, some DIY home alarms systems began offering monitoring services.
A non-monitored alarm is inexpensive and easy to install. It may have only a single door switch or just a motion detector to catch an intruder. When they trigger it, a loud alarm sounds.
Non-monitored alarm systems are available at a variety of stores, such as electronic and home improvement locations. Monitored alarms companies advertise heavily and often call homes in the area seeking to set appointments with the homeowners to present their system.