I am not completely familiar with the ADT system that you have. I do know that most systems including the ademco have system specific wireless components. Most wireless systems are hybrid (wired and hardwired). You can use you existing contact, motions, etc. but the keypads and main panel would need to be changed out. The keypads for the Ademco systems with the exception of the LYNX system can all be hardwired. I do not beleive you can use the Ademco wireless with you current system. A complete changeout is really only for a pro to do since there are monitoring center specific signals that must be sent. If it is to be a local only system you could attempt it yourself, but i would not recommend it because of the details required and very detailed programming to be done with the system.