'Telecommunication' is a term coming from Greek and meaning 'communication at distance' through signals of varied nature coming from a transmitter to a receiver. In order to achieve effective communication, the choice of a proper mean of transport for the signal has played (and still plays) a fundamental role.
In ancient times, the most common way of producing a signal would be through light (fires) and sound (drums and horns). However, those kinds communications were insecure and certainly left room to improvement as they did not permit message encryption nor a fast transmission of information on a large scale.
The true 'jump' in terms of quality came with the advent of electricity. Electromagnetic energy, in fact, is able to transport information in an extremely fast way (ideally to the speed of light), in a way that previously had no equals in terms of costs reliability. Therefore, we may say that the starting point of all modern telecommunications was the invention of the electric cell by Alessandro Volta (1800).
It was shortly thereafter that the first experiments on more advanced communication system begun. In 1809, Thomas S. Sommering proposed a telegraphic system composed of a battery, 35 wires (one for each letter and number) and a group of sensors made of gold, which were submerged in a water tank: when a signal was passing from one of those wires, electrical current would split water molecules, and small oxygen bubbles would be visible near that sensor. Many other experiments were soon to follow: Wheatstone, Weber and Karl Friedrich Gauss tried to further develop Sommering's idea in a product that could be mass-distributed, but their efforts were without success.
For the next step we would have to wait until 1843, the year in which Samuel Morse proposed a way to assign each letter and number to a ternary code (point, line, and space). This way turned out to be extremely convenient and more affordable than Sommering's idea, especially in terms of reduced circuitry (you wouldn't need anymore a wire for each symbol). Meanwhile, technology became advanced enough to find a way to convert those signals in audible (or sometimes graphic) signals. The combination of these two factors quickly determined the success of Morse's symbol code, which we can still find used today.
The system was further developed and improved in the following years by Hughes, Baudot, and Gray (1879), who theorized other possible codes (Gray's code has still applications today in the ICT industry and in barcodes technology).
However, the telegraph could still be used just by trained personal and in certain buildings like offices, so it could only be used by a limited amount of people. Research of the time therefore took another direction and aimed at producing a machine that could transmit sounds, rather than just signals. The first big step in this direction was the invention of transducers which could transform an acoustic signal into an electric one and vice versa (microphone and receiver) with acceptable information loss, in 1850.
Seven years later, Antonio Meucci and Graham Bell independently managed to build a prototype of an early telephone ('sound at distance') machine. Since Meucci didn't have the money to patent his invention (the cost was $250 at the time), Bell managed to register it first.
Both with telegraphs and telephones, the need for a distributed and reliable communication network soon became evident. Routing issues were first solved by means of human operators and circuit commutation: the PSTN (Public Switched Telephone Network) was born. However, this system didn't guarantee the privacy and secrecy of conversations, and efforts towards the development of an automatic circuit commutation were made.
In 1899, Almon Strowger invented an electro-mechanic device simply known as 'selector', which was directed by the electrical signals coming from the calling telephone device, achieved through selection based on geographical prefixes.
Many other innovations were soon to come:
- In 1885, Guglielmo Marconi invented the 'wireless telegraph' (radio);
- In 1920, valve amplifiers made their first appearance;
- In 1923, the television was invented;
- In 1947, the invention of transistors gave birth to the field of electronics;
- In 1958, the first integrated circuit was built;
- In 1969, the first microprocessor was invented.
With the last step, electronics becomes more than ever a fundamental part in the telecommunication world, at first in the transmission, and soon also in the field of circuit commutation.
Moreover, in 1946 the invention of ENIAC (Electronic Numerical Integrator and Computer) starts the era of informatics. Informatics and telecommunications inevitably begun to interact, as it was to be expected: the first made fast data processing possible, while thanks to second the data could then be sent to a distant location.
The development of microelectronics and informatics radically revolutionized techniques both in telecommunication networks and performance requirements for the networks. Starting from 1938, an innovative technology called PCM (Pulse Code Modulation) started to grow more and more popular. This technology could achieve the digital transmission of a voice signal by digitally encoding and decoding, rather than by means of transducers: however, PCM was first used on a large scale only in 1962 in the United States (the so-called 'T1').
During the mid Sixties Paul Baran, a RAND Corporation employee working on communication problems concerning the US Air Force, first gave birth to the concept of 'packet switching network' rather than the conventional idea of circuit commutation network. According to this model, there should be no hierarchy in the nodes of a network, but each node should rather be connected to many others and be able to decide (and, in case of need, modify) the packet routing. Each packet is a bulk of data which consist of two main parts, a 'header' containing routing information and a 'body' containing the actual data.
In this context Vincent Cerf, Bob Kahn and others developed, starting from the 70s, the TCP/IP protocol suite, which made possible communication of computers and heterogeneous machines through a series of physical and logical layers. Packet switching network and TCP/IP were later chosen by the military project ARPANET. The rest of the story is widely known: in 1983, ARPANET became available to universities and research centers, among which NSFNET (National Science Foundation + NET), which finally gave birth to the Internet.
In the latest years, the importance of the Internet has been constantly growing. The high flexibility given by the TCP/IP suite and the ISO/OSI protocols provide a strong foundation on which communication among devices of different kind -- be it a laptop or a cell phone, an iPod or a GPS navigator -- has finally been made simple and easy to achieve.