Download the manual. I can't remember if it is in the User's Manual or the Programming Manual but a sequence to reset the security code is detailed in one of them. Also, it soulds like the telephone line was wired through the system for full seizure. To defeat this, you will need to take it out of the phone lines at the outside telco box. How it is wired is that the alarm panel intercepts the telephone line first and then feeds the circuit back out to the main junction where the telco comes into the house.
The system is beeping. When I disconnect it, it shuts down my phone and internet. It's old, I don't have the security code (previous owner had it-he's deceased). I want to shut it down and keep my phone line working. Please help.