TELEPHONY _ ITS EVOLUTION AND PROSPECTS: FROM TELEGRAPHS TO VIDEOPHONES

20th Century Technology Series

The Twentieth Century Technology Series was planned as an opportunity to look back and reflect on the key developments in engineering and technology and their impact on society and the economy. The five speakers were asked to explain the basic principles behind their respective technology and describe how the technology evolved bringing it up to the present day, then speculate on technological prospects after the year 2000.

Victor Suchar, Series Organiser

TELEPHONY _ ITS EVOLUTION AND PROSPECTS: FROM TELEGRAPHS TO VIDEOPHONES

Graham Fisher, Strategy and Technology Manager, Orange Personal Communications plc, on 23 April 1999

Alexander Graham Bell is well-known in connection with telephony, but it is not widely appreciated that he first sent telegraph messages whilst living in Bath. He was born in Edinburgh in 1847 and in September 1866 was teaching at Somersetshire College at 11 The Circus, Bath and lodged at 22 Charles Street (appropriately opposite the present telephone exchange). He later moved to 18 and then to 21 Bennett Street and in 1867 sent a telegraph message between those two houses.

His father and grandfather both studied the human voice as an aid to teaching deaf people and Bell built on von Helmholtz's work which showed that vowel sounds could be synthesised using tuning forks driven by electric coils. His first patent, number 174 465, in 1876 was for an harmonic telegraph by which many messages could be sent down one set of wires. He also invented the first microphone and loudspeaker which used a diaphragm driven by a permanent magnet and coil system.

Edison, in America, developed the carbon microphone in 1878, which was much superior in performance to Bell's, so in 1880 the United Telephone Company was formed using Edison's microphone and Bell's receiver _ a system which continued unchanged for 100 years. In 1884 Davis & Sons, "plumbers since 1828", of Walcot Street were agents for this company in Bath and in 1886 the first telephone exchange was opened at 11a Union Passage with connections to Bristol.

The Ericsson Magneto Telephone, which generated the necessary current by a hand-operated magneto on the phone, so that you `rang up' and `rang off', continued in use until 1920. The answer `Hullo!' was derived from the hunting call. All exchanges were manually operated with each phone individually connected to it. With the growth of the number of phones an automatic exchange was developed, the Strowger, in 1889.

The speaker described the operation of such exchanges, the development of trunk lines, subscriber trunk dialing in 1967 and international dialing in 1976. Then he described the system used for mobile phones, which is now standardised over Europe and will shortly be global. The potential developments of mobile phones to give a large number of additional services is proceeding very rapidly and videophones with excellent picture and sound quality will be available very soon.

The discussion raised questions about the health risks of mobile phones, the ease of use by elderly and disabled people, the cost of calls to mobile phones, encryption and the financing of mobile phone networks, all of which the speaker answered. He pointed out the value to the emergency services of a network being able to locate a user to within 100 m when an accident was reported and the possibility of developing this to provide users with directions to the nearest service they require.

Don Lovell