The "coffee grinder," or dial telegraph as it was actually called, was used alongside the Morse telegraph at SJ from the very beginning in 1856. It was in use until 1913.

The sender set the crank to point to the first letter he wanted to send. Then he moved to the next letter, and so on. The same characters were then displayed on the receiving apparatus. The receiver had to write down the characters as they were displayed. Eventually, he could read the entire message. Before starting to send, a test signal had to be sent and the recipient's response awaited. If there was uncertainty about whether someone was present to read the message, there was a risk it would go unnoticed.