emptyhead

I did search. I found a couple of threads, but not any information that was helpful for me. It was mostly about existing systems and upgrades/changes. I'm just not sure where to even start. Do small self-contained systems even exist? Do I have to purchase lots of separate components, like a controller, tone generator, computer software, etc? I'm basically looking for something like an intercom system that I can program to signal the change of classes.

I'm not sure if this is the right place to post this. I am looking for a bell system for the small school where I work. I would like to place a controller in my office that I can program to operate (wired or wireless) speakers in 4 local classrooms. I am technology impaired - so layman's terms please. Thanks!