We have ADT's system in our commercial building and have had problems with it every since install. the latest problem..we were required to upgrade our analog cellular transmitter to a digital cellular transmitter. it cost me 300.00 to have this done about 6 months ago and just recently found out that it does not work. ADT did not even test it after they installed. Now they want me to pay service fees for having them fix it. i definitely would not install ADT in another building and am woring on getting them out of our current location.