Its 1923 and the phonograph has been around for 45 years, and local radio has been around for 3 in some areas, so I think they would know what an entertainment device is. A tracking device, like a radio that tells people where you are without your input. These idea would not go over the heads of any citygoer, though you would struggle with any back country folks.
What do you think they’d also do with it? They were already getting in arguments over mail with people they would never see nor hear.