Reminds me of the grills at the college I attended. The system used to be a very old Edwards system in the original wing, which had these grills with Unelco 4" bells for class change, and then the 6" Edwards 24 single stroke bells.
Here’s an example of a late 60s high school that used to have an old Edwards system. The plate is where the 10" single stroke bells used to be. I think there was a surface mount bell or horn next to the school bell, and then a clock system. Here is a picture of a typical IBM box, looks about the same size.
