That's difficult, could be cable , Amy of the detectors , bell box , PSU fault and so on
Hence why calling an engineer is quicker , you may have it displayed on keypad what the fault is when it goes off
Just pick any and delete the account details after so it isn't constantly trying to communicate somewhere
Although as GG said use non adt panel , or try
and update firmware
Well the PIR has alarm contacts so you could use them maybe with a relay just to trigger the input on any autodialer , there many cheaper devices which will do the just b for you on eBay
For example
https://www.ebay.co.uk/itm/Alarm-Installer-Auto-Dialler-with-Controllable-Relay-/233783581818?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0
They have different versions , but I would recommend a cheap monthly contract SIM , you will kill your credit quick otherwise
Unlikely
Would be interesting though , even with two independent sensors , the shock would suddenly be on access mode provided you can open the door with the shock activation, and or having an over zealous delivery driver come knocking on the door
So what about your
Smart TV
Car
Washing machine
The list can go on , and sure you can get sometimes odd password turn up on internet but your talking about a"security" device
Simply put if the sub wants the eng code then he should know that you hold no responsibility for the system and nothing is warranteed you would have to be crazy to do it
If they already have code it's difficult to take it from them, but if you have contract of service to provide them , I wonder does it comply when you have a contract that sub has access to main settings?
Alarm monkeys? Does it matter to your efficacy insurance that you allow the sub to keep the engineer code ? Or I am looking at it the wrong way ?