A good job on getting it open w/o destroying it.
I have a few things from my career as a firefighter/paramedic, now retired. I don't have a communications-box like that. I do have a vintage fire bell, it came out of an old Miami-Dade County (FL) public school. I got it from an acquaintance who is an draftsman, and a project manager for a company which does a lot of public school renovations. He pulled this and a couple others out of the dumpster.
I mounted it in-between my garage doors, and I have-to lift-up my little grandsons to pull the striker actuator (the red metal strap hanging vertically from the right-lower corner of the bell). I call it the "Pizza Bell." When the grandsons want pizza, they ask to ring the bell. It takes a healthy pull and release, but that results in a satisfying, "clang!" Pizza-time!
The manufacturer is Bevin Brothers. I suspect that it may be pre-WW II. I assume it's been re-painted at some point, I've left it as I got it.