ADT doesn't monitor the system at all. The transformer they provided to us wasn't working and we lost the battery because of that. They couldn't detect weather our system was still working or not. I called them after three weeks to notify them about the failure. The reply i was getting them was bull-###. I wonder how easy it would be for a bugler to break the system from out side and get into home, or what would happen if fire broke out in my house... They don't even monitor all these. We have been having the system installed for almost two years now, and we have not received the yard sign that says secured by ADT. We have requested at least 5 times. but, Fu... A... takes our complains do nothing about it. We got the system in october 2007 and it is july 2009. No service, No yard sign.
After being fed-up with the service, i asked them to cancel my contract and now they are charging the contract termination fee which is more that my payments for remaining months. So, i decided to keep the service as it is cheaper that way.
Never go for ADT system. I hope they all die in hell!!! Do some research on the other competitors. ADT sucks!!!