old alarm

So growing up, it was common to see alarm bell/siren boxes like the photo below. They are not so common today as far as I can tell. What caused them in the style below to go out of fashion and why?

I've just moved into a property with a house alarm. Previous owners did not leave any information or manuals other than the code to activate/deactivate. Hoping some of you guys, with years of experience, can help me with the following questions; 1.) Can anyone identifiy what alarm this is so I...