Edison, well known for (kind of inventing, but also kind of stealing) the phonograph and the incandescent light bulb, had some less commercially known products that never quite hit the shelves of the modern era, in this case, a phone that can allow communication with the dead.
His research in this spooky realm wasn’t publicized until 1949 (long after his glory days). A French edition of his original diary was discovered and translated in much fuller detail, revealing some new interesting research and information of the ghost variety.
This research to develop ghost phones was primarily done in 1870 by greatly amplifying some of his phonographs. He was so certain it would work, he made a death pact of sorts with one of his engineers, that whichever one of them died first, the other would use the spirit phone to contact the other, from beyond the grave.
Whether Edison actually talked to any ghosts is uncertain, I’d like to imagine he’s the “unknown caller” ID that always calls my phone.