156 Alarm System

A good Alfa day to one and all.
The question,
Alfa 156 2.0 ts sw 2001.
Anyone know what make the alarm /security system is ? AR told me it is
a Thatcham cat 1,
but not the makers name, eg, serpistar, microscan, get the f**koff my
car.

This is the type with the black switchblade key fob.
The reason I ask is that I am thinking of adding in one of those pager
systems.
You know the one that buzz,s on a receiver and tells you to grab your
shotgun,
or baseball bat, as some s***head is about to mess with your car.
The usual question is,, can one of these "pagers" be connected to the
factory alarm system, (by the way where is the main alarm unit on the
car) ? the black box ...
Any one with this knowledge or even if you have tried a pager on your
alarm, please advise.
Regards and Thanks Martyn