Ages ago, I made up what I called a bell box for use on a very low budget TV soap which I helped to set up on the technical side. Consisted of a door bell, ding dong and buzzer, all standard units. And also a Maplin electronic door bell with a choice of rings. All in one box and battery powered. Got the idea from BBC TV where they were common in the old days. Dunno about now.
Came across it and thought it would make sense to get it to a good home where it would be used. Amateur dramatics? School plays or whatever?
Anyone know what such a thing was called in the theatre?