Telephony Timeline: the first 120 years
Before the telephone, direct communication between two people by speaking and listening, meant being in the same place. With the invention of the “electrical speech machine”, telecommunication was born and spread rapidly. People could now talk to one another across towns, countries and even across the world.
- 1861 – German schoolmaster, Philip Reis demonstrates a primitive speech transmitter
- 1876 – Alexander Graham Bell perfects the accoustic transducer and patents his telephone.
- 1879 – Thomas Alva Edison invents a carbon microphone, far superior to the one used by Bell
- 1880 – Bell and Edison amalgamate. Edison’s microphone is incorporated into Bell’s telephone resulting in the instrument in use for over a century.
- 1881 – The Government authorises the Post Office to offer a public telephone service. The first exchange opens in Swansea.
- 1889 – Almon B Strowger, an undertaker from Kansas City invents the Automatic Exchange.
- 1912 – Britain’s first dial telephone exchange opens in Epsom, Surrey.
- 1915 – First US coast-to-coast long-distance telephone call, facilitated by a newly invented vacuum tube amplifier, ceremonially inaugurated by Alexander Graham Bell in New York City and his former assistant Thomas A. Watson, in San Francisco, California.
- 1918 – The Strowger automatic telephone exchange is adopted as standard in Britain.
- 1936 – TIM, the speaking clock makes his debut in London
- 1937 – The 999 emergency service is introduced in London and subsequently throughout Britain.
- 1956 – The first Transatlantic telephone cable is laid between Oban and Clarenville, Newfoundland.
- 1958 – STD (subscriber trunk dialling) is introduced.
- 1966 – The Post Office Tower (now Telecom Tower) opens. Britain’s tallest building (189m) is a microwave relay tower, capable of handling over 150,000 simultaneous telephone calls and over 40 television channels.
- 1980 – Britain’s first “system x” all electronic, digital telephone exchange opens in London.
The telephone dates from 1876, when Alexander Graham Bell patented the first practical instrument. Bell’s telephone consisted of an electromagnet and a metal diaphragm. Two such instruments were required, one for transmitting and another for receiving. These were connected by wire to an exchange. Shortly afterwards, Bell’s electromagnetic microphone was replaced by the far superior carbon microphone patented by Thomas Alva Edison.
The microphone converts the sound waves of the sender’s voice (variations in air pressure) into an electrical signal (variations in current) which can be transmitted along a pair of wires to the receiver, where they are converted back into sound waves by the earpiece. Although the basic components remain the same – transmitter/microphone (mouthpiece) and receiver (earpiece) – the telephone’s appearance has changed considerably since Bell’s time.
The next major development was in the exchange that was necessary to connect widely dispersed telephone users to each other. The automation of this process was initiated in 1889 by Almon B Strowger, a Kansas City undertaker who was facing bankruptcy. He believed that an operator in the local telephone exchange was diverting his business enquiries to her relative, a rival undertaker. This called for drastic action to eliminate the human element! After much experimenting, with circular shirt-collar boxes and matchsticks Strowger came up with an ingenious design of a rotating switch with any number of contacts – one for each line. The switch was moved magnetically. Engaged lines contained certain voltages which powered the switch to move on until it reached a free line. This formed the basis of all electromagnetic exchanges used throughout the world for over a century.
Shortly before the turn of the 20th century, the candlestick telephone was introduced. This used a magneto system, which meant that the phone was connected to a large wooden box called a “subset” containing a battery, bell, and crank. The all-in-one hand combination set, combining microphone and earpiece in one handset, appeared in 1929. It looked modern and was more comfortable to use. Improvements over the years led to various lightweight moulded plastic designs produced in many colours.
The use of short-range radio links for telephones has created the mobile phone networks which are now so familiar. While these are sophisticated ultra modern systems, we should remember that they use the theory of radio communication based on the pioneering research of James Clerk Maxwell and have the same basic elements as the telephone of Alexander Graham Bell.