Telecommunications, also known as telecom, is the exchange of information over significant distances by electronic means, referring to all types of voice, data and video transmission. This is a broad term that includes a wide range of information-transmitting technologies and communications infrastructures, such as wired phones; mobile devices, such as cellphones; microwave communications; fiber optics; satellites; radio and television broadcasting; the internet; and telegraphs.
A complete, single telecommunications circuit consists of two stations, each equipped with a transmitter and a receiver. The transmitter and receiver at any station may be combined into a single device called a transceiver. The medium of signal transmission can be via electrical wire or cable -- also known as copper -- optical fiber, electromagnetic fields or light. The free space transmission and reception of data by means of electromagnetic fields is called wireless communications.
Types of telecommunications networks
The simplest form of telecommunications takes place between two stations, but it is common for multiple transmitting and receiving stations to exchange data among themselves. Such an arrangement is called a telecom network. The internet is the largest example of a telecommunications network. On a smaller scale, examples include the following:
- corporate and academic wide area networks (WANs);
- telephone networks;
- cellular networks;
- police and fire communications systems;
- taxi dispatch networks;
- groups of amateur (ham) radio operators; and
- broadcast networks.
Data is transmitted in a telecommunications circuit by means of an electrical signal called the carrier or the carrier wave. In order for a carrier to convey information, some form of modulation is required. The mode of modulation can broadly be categorized as either analog or digital.
In analog modulation, some aspect of the carrier is varied in a continuous fashion. The oldest form of analog modulation is amplitude modulation (AM), which is still used in radio broadcasting at some frequencies. Digital modulation actually predates AM; the earliest form was Morse code. Modern telecommunications use internet protocols to carry data across underlying physical transmissions.
Telecommunications industry and service providers
Telecommunications systems are generally run by telecommunications service providers, also known as communications service providers. These providers historically offered telephone and related services and now offer a variety of internet and WAN services, as well as metropolitan area network (MAN) and global services.
In many countries, telecom service providers were primarily government-owned and -operated. But that is no longer the case, and many have been privatized. The International Telecommunication Union (ITU) is the United Nations (UN) agency that administers telecommunications and broadcasting regulations, although most countries also have their own government agencies to set and enforce telecommunications guidelines. In the United States, the Federal Communications Commission (FCC) is the primary regulatory agency.
There is a large umbrella of companies that provide different types of telecommunications services, including internet service providers (ISPs), telecom equipment providers, wireless service providers, radio and television broadcasters, cable companies, satellite television providers and managed service providers (MSPs).
The three main segments within the telecom industry are manufacturers of telecom equipment, telecom services and wireless communications. Within these sectors, telecom equipment -- which includes customer equipment, such as routers and modems; transmission equipment, such as transmission lines and wireless semiconductors; and analog or digital public switching equipment -- is the largest, and wireless communications is the smallest.
Large global service providers include the following:
- Nippon Telegraph and Telephone (NTT)
- China Mobile Limited
- Deutsche Telekom AG
- SoftBank Group
- China Telecom
- Telefónica SA
- América Móvil
Recently, service providers have been focusing on growing services, such as data and video, as opposed to voice communication services.
History of telecommunications
The word telecommunications comes from the Greek prefix tele-, which means "distant," combined with the Latin word communicare, which means "to share." Important telecommunication technologies include the telegraph, telephone, radio, television, videotelephony, satellites, closed computer networks and the public internet.
- 1876. The first telephone was invented by Alexander Graham Bell. This early model required an interpreter, or telegrapher, at both ends. These first telephones were intercom systems, where two phones were connected directly.
- 1877. The invention of the switchboard exchange telephone system enabled any combination of two phone lines to connect and talk with each other.
- 1891. Dial telephones were invented, which bypassed the need for an operator on each call. This made it much quicker and easier to make calls via telephone.
- 1947. The transistor was invented, which led to the development of modern electronics, such as computers and calculators.
- 1948. Microwaves began to be used to transmit phone signals, in places where phone wires did not exist.
- 1960. Phones began to transition from mechanical switching to electronic switching, which enabled features such as voice messaging, speed dialing and caller ID.
- 1984. The Bell System, which provided AT&T with a near-monopoly over telecommunications services in the U.S., was broken up, opening up space for competition for other providers.
- 1984. Cellular and personal communications service (PCS) phone use, which offered mobile communications beyond two-way radio use, was introduced.
- 1990s. Use of the modern internet became widespread.
- 2000s and beyond. The first decade of the 2000s saw mobile phones grow increasingly sophisticated. By 2012, smartphone usage was widespread.