I understand that conventional unmonitored alarm system has 3 major components - keypad (to arm/disarm etc),control panel (which monitors sensors and sets an alarm when armed), dialer (if you want to call outside).
I understand 'proper' system will have keypad separated from control panel and the control panel should be in a metal box in less accessible and visible place. so it should take sometime for an intruder to find it and smash it.
however the question - what do you do with dialers? there are not a lot of places where the land line socket can be placed in the property hence intruder simply need to go quickly around (dialing a number and playing message should take at least 20-25 sec) and smashing the dialer.
Also I understand it is fairly easy to cut US land line.. How protected land lines in the UK ?