Wall telephone with battery box, with Delville transmitter and magneto calling, unknown maker, 1880-1940.
Wall telephone with battery box, Delville transmitter and magneto calling, unknown maker, 1880-1940.
Early telephones used batteries for producing the speech currents and a hand-cranked magneto for generating the alternating current needed to ring the bells. To make a call the caller turned the magneto a few times and then lifted the handset. The operator connected the call manually using cords and plugs at the switchboard. At the end of the call both users turned their magnetos again to signal to the operator that they had finished. This was called 'ringing off'.