Local-battery telephone

This is the very first mass-produced type of telephone. It provided a connection between two fixed places. If more users had to be selected, a manual telephone exchange would be necessary. By rotating the crank, a small alternator produces electric current which supplies the bell in the opposite telephone. By picking up the earphone, a direct current voice circuit supplied by a battery would be switched on. Each telephone had its own battery, hence the name of the system. These telephones are still in use in the army, on railways, mines etc.

Please, put the earpiece back onto the telephone after you finish your conversation.