The THGs member Graeme Marrett has written two articles for the THG Journal; this article is a very condensed version of his excellent history ‘The evolution of switching systems’ published in the Spring and Summer editions [ISSN 1353-0097 number 114 and 115].
The first manual switchboards were simple affairs both technically and operationally for there were few customers and they served a very local community with no connections to other telephone systems. The customer had a simple telephone powered by a non-rechargeable battery housed in (or near) the telephone.
How it worked
To use the phone the customer lifted the receiver from its hook and waited for the operator to answer and ask for the number (or name) of the person required. The switchboard worked by a the operator throwing switches or putting in plugs to connect the two parties. The operator had no indication when the call had ended and various manual record keeping methods were used to record that the call was in progress. There was no metering of the calls duration.
As more and more customers joined the system the switchboard soon became full and another had to be added. This meant there was a problem, some calls needed to be passed between switchboards adding to the time taken to set up the call and clear it down when it was over. The next evolution was the ‘multiple’ switchboard, where all the operators had access to all the lines for completing the call; but only had a selection of lines from which calls originated.
The switchboard comes of age
In the ‘local battery’ system, the customer had a battery in the telephone. In those days most homes did not have an electricity supply. The maintenance of the battery in the customers telephone was also a problem, requiring visits to change the battery The battery was required for speaking and for calling the operators attention. The operator called the customers attention by sending a signal down the line to ring the bell in the customers telephone.
In the ‘central battery’ system the power for speaking came from a ‘central’ battery in the exchange, but this left a problem of how the customer called the operator; formally the one of the functions of the local battery. In the ‘central battery system, to call the operator the user had a hand cranked generator.
Eventually the hand generator was replaced by a device in the exchange being able to detect when the customer lifted the receiver from the hook and when they replaced it thereby giving the operator a signal that they wanted to make a call and when they had finished the call.