Your main option is
https://www.securitywarehouse.co.uk/catalog/intruder-alarm-c-36/security-control-panels-c-36_102/control-panels-all-c-36_102_41/honeywell-galaxy-dimension-spi-key-gd48-p-2078.html
Everything else installer based only, however if you can prove to them your an installer it would be different
Ok I misunderstood, as I am dodgy engineer who doesn't read things ,I though you meant to answer a call you need to u lock the phone , but yes apps don't unlock phones ,
I assume a rooted phone with special app would do it , same way trusted devices settings unlock the phone you might get an app that is trusted and phone unlocks when it rings it , not seen the latter tho , or tried
So if it's engineer reset , once you open it you won't be able to reset it , so no harm in trying but have an engineer prepared so you know what's coming , he can test your system fully same time
So your trying to get the alarm to stay working and also get a signal from the pirs to your ha?
Short cut meesed up way of doing it , however , you need to upgrade to an alarm that is capable
Why don't you just fit the pirs available for your ha , and keep the intruder separate ?
They would have been offered an upgrade by most over the years , but sadly most don't want to pay for it
Instead they pay over the years and then the standard comment comes out ,cof how much they been paying over the years could have bought them lots of alarms
Reality check, it's been working for years because they have been paying someone to maintain it , and they can't fix it without you upgrading
Pay for a new alarm simple.
Or more like this panel is scrap, there is no contract for your alarm system , that seems clear , maintainer wasnt meant as a person who comes to fix it for you on request only.....
Scrap it
For alarms tampers etc. , I guess you could use an output card , Id bus relay board or op card mini , then there is the zones , if to many zones it might be difficult , zone mapping will help you , have u got engineer access? Then you need enough inputs on Ur ha , unless someone knows hkc is integrated in another way, but didn't think so ..