6-line switchboard (1880s) : connection plugs

As well as the public telephone system, there were a great number of private networks dotted around Britain. These could be in offices, businesses or large houses and sometimes had no connection to the outside world.

This is the sort of switchboard that would have been perfect for the job. It could be connected to up to six telephones at a time, via the screw terminals on top, perhaps with one terminal connected to the public network.

The indicators on the top level showed the operator when a caller wanted attention. Connecting calls was easy. Each phone was connected to each of the five horizontal bars, so the operator could select any available bar and insert plugs under the two relevant numbers. This completed a circuit and made the connection. This is the principle for all switching, whether it is with a cord, mechanically or digital.