Concept

Telephony

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Telephone company

A telephone company is a kind of communications service provider (CSP), more precisely a telecommunications service provider (TSP), that provides telecommunications services such as telephony and data communications access. Many telephone companies were at one time government agencies or privately owned but state-regulated monopolies. The government agencies are often referred to, primarily in Europe, as PTTs (postal, telegraph and telephone services). Telephone companies are common carriers, and in the United States are also called local exchange carriers.

Backbone network

A backbone or core network is a part of a computer network which interconnects networks, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas. Normally, the backbone's capacity is greater than the networks connected to it.

Echo suppression and cancellation

Echo suppression and echo cancellation are methods used in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. In addition to improving subjective audio quality, echo suppression increases the capacity achieved through silence suppression by preventing echo from traveling across a telecommunications network. Echo suppressors were developed in the 1950s in response to the first use of satellites for telecommunications.

Trunking

In telecommunications, trunking is a technology for providing network access to multiple clients simultaneously by sharing a set of circuits, carriers, channels, or frequencies, instead of providing individual circuits or channels for each client. This is reminiscent to the structure of a tree with one trunk and many branches. Trunking in telecommunication originated in telegraphy, and later in telephone systems where a trunk line is a communications channel between telephone exchanges.

Wideband audio

Wideband audio, also known as wideband voice or HD voice, is high definition voice quality for telephony audio, contrasted with standard digital telephony "toll quality". It extends the frequency range of audio signals transmitted over telephone lines, resulting in higher quality speech. The range of the human voice extends from 100 Hz to 17 kHz but traditional, voiceband or narrowband telephone calls limit audio frequencies to the range of 300 Hz to 3.4 kHz.

Disruptive innovation

In business theory, disruptive innovation is innovation that creates a new market and value network or enters at the bottom of an existing market and eventually displaces established market-leading firms, products, and alliances. The term, "disruptive innovation" was popularized by the American academic Clayton Christensen and his collaborators beginning in 1995,, but the concept had been previously described in Richard N. Foster's book "Innovation: The Attacker's Advantage" and in the paper Strategic Responses to Technological Threats.

Remote concentrator

In modern telephony a remote concentrator, remote concentrator unit (RCU), or remote line concentrator (RLC) is a concentrator at the lowest level in the telephone switch hierarchy. Subscribers' analogue telephone/PSTN lines are terminated on concentrators. They have three main functions: Digitize: convert voice (and sometimes data) from analogue to a digital form. Connect off-hook lines to the local exchange — the concentration function. Multiplex, interleaving many calls together on a single wire or optical fiber.

History of the telephone

This history of the telephone chronicles the development of the electrical telephone, and includes a brief overview of its predecessors. The first telephone patent was granted to Alexander Graham Bell in 1876. Before the invention of electromagnetic telephones, mechanical acoustic devices existed for transmitting speech and music over a greater distance. This distance was greater than that of normal direct speech. The earliest mechanical telephones were based on sound transmission through pipes or other physical media.

Telephone jack and plug

A telephone jack and a telephone plug are electrical connectors for connecting a telephone set or other telecommunications apparatus to the telephone wiring inside a building, establishing a connection to a telephone network. The plug is inserted into its counterpart, the jack, which is commonly affixed to a wall or baseboard. The standards for telephone jacks and plugs vary from country to country, though the 6P2C style modular plug has become by far the most common type.

E.164

E.164 is an international standard (ITU-T Recommendation), titled The international public telecommunication numbering plan, that defines a numbering plan for the worldwide public switched telephone network (PSTN) and some other data networks. E.164 defines a general format for international telephone numbers. Plan-conforming telephone numbers are limited to only digits and to a maximum of fifteen digits. The specification divides the digit string into a country code of one to three digits, and the subscriber telephone number of a maximum of twelve digits.