Find a cheaper company if costs are a cause of concern.
Can tell you if ADT installed the system then there's a good chance it's not clean as we say,so when you attempt a default it will boot back up to Aunty,their software to safeguard their settings,codes etc.
Seek advice from a pro alarm company who can advise on what and can't be done or replace the panel.
As a matter of interest what model panel you got because ademco have over a dozen out there?.
e manno, January 2014