THE HISTORY OF THE TELEPHONE SYSTEM

3. THE ADVENT OF AUTOMATIC TELEPHONE SWITCHING SYSTEMS

For a long time after the introduction of the telephone, subscribers , as they were called, depended on all their connections on switchboards with human operators, usually girls. But as the system grew, the operators became very busy particularly at peak periods and delays in answering calls was an increasing source of annoyance. Wrong connections were frequent and in the rush to connect calls, conversations were occasionally cut off by mistake.

One of the earliest subscribers in America was Almon B. Strowger, a funeral parlour proprietor of Kansas City who, it is said, discovered that his local telephone operator was married to his rival undertaker to whom she diverted Strowger's calls.

In 1889 he invented a 'Step-by-step' automatic system and all early automatic exchanges were based on 'Strowgers' principle,

using a dialling disc, which became known as a DIAL which was in use throughout the world until the advent of the Keypad in the 1980's.

By turning the dial,whose finger holes are marked with the digits, the caller 'routes' his connection through several switching stages,selecting the exchange, the group of lines, and finnally the number he wants, at the same time switching on the current operating the bell and the ringing signal ( tone) or the 'engaged' tone

Today, this system has been extended and developed that one can ring up, without human help, telephones in most other countries and continents.
A Uniselector mechanism
A typical 'two-motion' Selector mechanism

It does not matter if those in other countries use a different system of automatic routing such as , for instance, the 'Panel ' system that used to be used in New York and other American towns, in which the connection is made by motor-driven units; the 'Crossbar' which works with relays and a matrix layout; the 'Rotary' system which has electro-magnetic clutches or the ever developing ' Electronic Systems' based on electronic computor techniques which establish the connection within a fraction of a second and are much more reliable than the earlier electomechanical systems.

( This section is being developed - please be patient & try again later ......Ed. )