This is in a house built in 1955, not sure if it is original or not. This part is located in the master bedroom and there is(was) a speaker at the front door that was disintegrated. Can’t find a microphone or button at either end and all the knob does is twist(volume?)

Trying to figure out what it is and what I should do with it. Fix it or fill it in. If it’s an intercom, might try and find parts. There is no name or part number on any of it.