It's a phone handle with a jack input soldered to the piezo speaker. You can use it as a lofi speaker as well as a telefone mic. Or it might be a start to make your own "Dial Tone Assembly" - I attached the arduino code for it.
With all proceeds going to benefit Ukraine, the latest from Angela Winter is a beautifully haunting work that centers the human voice. Bandcamp New & Notable Apr 16, 2022