Telephone

History

The invention of the telephone is allotted to Alexandre Graham Bell. One knows several precursors to him, of which:

In France, Charles Bourseul, agent of the Télégraphe poses the principle of the telephone. An article of the Illustration presents its explanations the August 26th 1854.
Philippe Reis, in a declaration with the Company of physics of Francfort-sur-le-Main, pronounces the word “telephones” the October 26th 1861.
In the United States, Italian-American the Antonio Meucci would have preceded 16 years Bell.

The telephone was exploited commercially with the the United States as of 1877 and, in France as of 1879. In 1912, one counts 12 million telephones in the world including 8 million in the United States. There was an subscriber for 12 inhabitants in the United States, 1 per 71 in Great Britain and in the German Empire and 1 per 183 in France.

The manually-operated telephone system

At its beginnings, the phone network is entirely manual. The call of a correspondent is carried out by the following procedure:

the subscriber takes down compound of his telephone,
this action causes the fall of a Volet heralding with the exchange sometimes lighting a Voyant.
an operator answers the subscriber, notes the number of the correspondent to be called;
if the correspondent depends on the same exchange, connection with the subscriber will be done in “room”;
if not, the operator calls another operator in charge of the exchange of fastening of the person called;
when called is joined, the operators connect the two subscribers.

The button of call was gradually replaced by a magneto . Its role is to produce an electric tension intended to make fall the shutter heralding the exchange. The advantage compared to the button of call is the suppression of one of the piles present at the subscriber whose maintenance was particularly expensive.

The dial telephone

The dial telephone was invented by Almon Strowger, with the the United States towards 1891. This one, contractor of Undertaking, suspecting the operators of privileging her competitor, wanted to eliminate the manual operations during the establishment of a communication. The automatic switch will be tested in France as of 1912 with Nice.

The advantage of the dial telephone is to directly call a correspondent without passing through an operator. The user takes down compound of his telephone transmits to a machine, using a mobile dial, the series of figures identifying his correspondent (its phone number).

At the time of the passage to the automatic in Paris region, a number with three digits was associated with each Telephone center. The subscribers were to compose these three figures, then the number of their correspondent. However, one kept the practice a long time, by giving his number, to give the name of the exchange and not the corresponding number.

Mobile telephony

VoIP

The apparatus

The fixed telephone

The telephone is composed historically of 2 blocks:

a case containing the transmission system of the word, very often a system of Ringing to announce a call and a dial or a keyboard allowing a dialog with the telephone center. This dialog is carried out by composing the number of another subscriber. The switch of the exchange answers it by sending tonalities of acceptance, refusal or routing. In France, the tonality of routing at summer removed the October 18th 1996 with 23:00, at the same time as classification passed to ten digits;
a compound which makes it possible to exchange the its S of the voice between the two interlocutors on the phone line. The combined block is composed of two parts: a Microphonous part which is placed in front of the mouth and a loudspeaker part which is placed near the ear. The compound is a relatively recent invention: in the first times, the interlocutor spoke in front of a wood plate interdependent of the case or, according to the case, in a small funnel, while carrying to his ear the ear-phone connected to the case by a wire.

With the evolution of electronics HF and techniques Numerical S, the telephones of interiors are from now on without wire. One or (several) combined of reduced size communicates by a radio contact on carrying a UHF or VHF with a bases connected to the phone line. This connection can be numerical, for example for the stations DECT

The telephones can be equipped with screens text posting various information.

They do not use inevitably any more the Phone network commutated (STN), and can be connected on the networks IPv4 and IPv6.