This was a portable phone for the miners in 1955 to send emergency signals. The phone could be connected with the cable network, or miners could send an emergency signal by turning the knob as indicated in the 3D model with some "woof woof" sound for warning.
Location: [Nederlands Mijnmuseum](http://https://www.nederlandsmijnmuseum.nl/), Heerlen (Limburg)
Created by: Yuen Fei, Li