ADT don't use their own software,they only change the default codes.
This is to stop what you are asking possible,you need to contact ADT and find out if the alarm still belongs to them,or the previous owner has purchased it.
If the owner has purchased the alarm, they will not give you the required code.
They will only be interested in selling you a monitoring contract,or charging you a stupid amount of money to decommision it.
If the previous owner has purchased this alarm there's nothing to stop you finding another alarm company to take it over.
The line fault is a coms/line failure as this is the monitoring service which has been terminated.
Get an engineer in he can crash it and restore factory defaults and deactivate the coms,all for a fee of course.
no name
February 2012