ADT kind of sucks. When I was a Restaurant manager we used it and I had problems with it (Phantom alarms in the middle of the night - after 2nd one was a 50$ fine)
One of the other stores had the same system and a guy drove a car through the front door and man-handled the safe out (that was bolted to the floor... so it took some time) and away he went - cops didn't get there til like 30 min later (reporting delay.....)
This is the biggest (funniest) Fail. One morning I go in to open up and do AM prep. I go to enter the # to turn off the alarm and the number pad falls off the wall. So there I Was, Alarm screaming behind me trying to figure out how to hook the number pad back up and get the alarm turned off before the cops came and shot me in the ass....
Of course the thing used some kind of weird connectors that were a PITA to re connect
The older systems required a phone line so somebody could cut your phone connection and ransack your place - the alarm would go off but no notification would go out..