Telephone > Manual switching
Before the advent of Automatic Switching, all Telephone Connections were made by hand at the Manual Switchboard, Figure 1. The Calling Customer rang up an Operator, at a Switching Office, which, after knowing the number of the Called Customer, interconnected the corresponding Lines, to Close the Circuit, in order to complete the Call.
Figure 1: Manual Switchboard
As the Telephone Systems became more sophisticated, the Automatic Switching replaced this direct intervention by the Telephone Operator.
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Telephone > Manual switching