They worked by creating ‘clicks’ the rotating bar analog switches could ‘hear’. Each rotation back to “O” ‘told’ the switch the digit based on the clicks back to “O”. These old switches could accommodate 3 to 7 digit dialing with no issues. It took the newer versions to to handle 1+ 10 digit dialing. Otherwise the operator had to connect an interexchange (long distance) call.
People knew their local exchange name. We were Elgin and then Pelham. You could ‘dial’ 4 digits within the exchange to call a neighbor or 7 digits to call another local exchange. Thus we were 0178 and 5550, respectively.
These rotating bar switches obviated the local operator to complete a local call. The switches connected physical wires, circuits, to make an electrical connection to a specific residence or business set of wires. No more operator plugging A to B. The plug (then switch) connected a pair of wires called tip and ring, a terminology that persisted for decades, even when the technology advanced to digital switches, as did the term twisted pair.
Rings were caused by 40 volts DC flowing down that circuit . That voltage could knock you on your butt.
You didn't take Pelham 123?