How do burglars alarms work?

Question

any complaints abt ebay?

Answer 1

If you are refering to ADT. I do know how they works. I used to work for them as sales person. Ermm.. they will attach a sensor at your door, so once anyone force open the door the main system will detect and it will auto send a signal to the guarding office which the people there will contact the respective side to ask for assistant to come down to your place.

Answer 2

motion dector... i think...