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Telephone Keypad
A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell System in the United States in the 1960s – this replaced rotary dialing, that had been developed for electromechanical telephone switching systems. Because of the abundance of rotary dial equipment still on use well into the 1990s, many telephone keypads were also designed to be backwards-compatible: as well as producing DTMF pulses, they could optionally be switched to produce loop-disconnect pulses electronically. The development of the modern telephone keypad is attributed to research in the 1950s by Richard Deininger under the directorship of John Karlin at the Human Factors Engineering Department of Bell Labs. The modern keypad is laid out in a rectangular array of twelve push buttons arranged as four rows of three keys each. For mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numeric Keypad
A numeric keypad, number pad, numpad, or ten key, is the calculator-style group of ten numeric keys accompanied by other keys, usually on the far right side of computer keyboard. This grouping allows quick number entry with right hand, without the need to use both hands on number row of main keyboard. On a standard IBM PC keyboard, numpad has 17 keys, including digits to , (addition), (subtraction), (multiplication), and (Division (mathematics), division) symbols, (decimal point), , and keys. On smaller keyboards (such as those found on Laptop, laptops), the numeric keypad can be implemented as alternative markings on alphabetic keys (usually --, --, --) or added as a separate unit, that can be connected to a device by means such as USB; some of these may include keys not found on a standard numpad, such as a spacebar or a (or ) key. Sometimes it is necessary to distinguish between a key on the numpad and an equivalent key elsewhere on the keyboard. For example, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Numbers In The United Kingdom
In the United Kingdom and the Crown Dependencies, telephone numbers are administered by the Office of Communications (Ofcom). For this purpose, Ofcom established a telephone numbering plan, known as the ''National Telephone Numbering Plan'', which is the system for assigning telephone numbers to subscriber stations. Telephone numbers are of variable length. Local numbers are supported from landlines. Numbers can be dialled with a '0'-lead prefix that denotes either a geographical region or another service. Mobile phone numbers have distinct prefixes that are not geographic, and are portable between providers. Structure All mobile numbers, nearly all geographic numbers, and nearly all non-geographic numbers have ten national (significant) digits after the trunk code ''0''. The overall structure of the UK's National Numbering Plan is: A short sample of geographic numbers, set out in the officially approved (Ofcom) number groups: In the United Kingdom, the "area code" is o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Number
A telephone number is the address of a Telecommunications, telecommunication endpoint, such as a telephone, in a telephone network, such as the public switched telephone network (PSTN). A telephone number typically consists of a Number, sequence of digits, but historically letters were also used in connection with telephone exchange names. Telephone numbers facilitate the switching and routing of telephone call, calls using a system of destination code routing. Telephone numbers are entered or dialed by a calling party on the originating telephone set, which transmits the sequence of digits in the process of signaling to a telephone exchange. The exchange completes the call either to another locally connected subscriber or via the PSTN to the called party. Telephone numbers are assigned within the framework of a national or regional telephone numbering plan to subscribers by telephone service operators, which may be commercial entities, state-controlled administrations, or ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
All-Number Calling
All-number calling (ANC) is a telephone numbering plan that was introduced into the North American Numbering Plan by the Bell System in the United States starting in 1958 to replace the previous system of using a telephone exchange name as the first part of a telephone number.Blair N.D., Cosgrove M.P. (AT&T), ''why all numbers?'', Bell Telephone Magazine, Autumn 1962, p.10 The plan prescribed the format of a telephone number assigned to subscriber telephones to consist of ten digits, composed from a three-digit area code, a three-digit central office code, and a four-digit station number. This increased the number of effectively available central office codes in each numbering plan area (NPA) from 540 to 792, thereby staving off the threat of exhausting the number pool, which was forecast to occur by the late 20th century. History Until the 1950s, a typical telephone number in the United States and many other countries consisted of a telephone exchange name and a four- or five-di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Exchange Names
A telephone exchange name or central office name was a distinguishing and memorable name assigned to a telephone exchange, central office. It identified the switching system to which a telephone was connected, and facilitated the connection of telephone calls between switching systems in different localities. While small towns and rural areas might each be served by a single exchange, large cities were served by multiple switching systems, either distributed in the community constituting multiple exchange areas, or sometimes hosted in the same building to serve a densely populated area. Central offices were usually identified by names that were locally significant. The leading letters of a central office name were used as the leading components of the telephone number representation, so that each telephone number in the area was unique. These letters were mapped to the digits of the dial, which was indicated visibly on the dial's numbering plate. Several systematic telephone numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Keys
A telephone, colloquially referred to as a phone, is a telecommunications device that enables two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from and (, ''voice''), together meaning ''distant voice''. In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice at a second device. This instrument was further developed by many others, and became rapidly indispensable in business, government, and in households. The essential elements of a telephone are a microphone (''transmitter'') to speak into and an earphone (''receiver'') which reproduces the voice at a distant locati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Exchange
A telephone exchange, telephone switch, or central office is a central component of a telecommunications system in the public switched telephone network (PSTN) or in large enterprises. It facilitates the establishment of communication circuits, enabling telephone calls between subscribers. The term "central office" can also refer to a central location for fiber optic equipment for a fiber internet provider. In historical perspective, telecommunication terminology has evolved with time. The term ''telephone exchange'' is often used synonymously with ''central office'', a Bell System term. A central office is defined as the telephone switch controlling connections for one or more central office prefixes. However, it also often denotes the building used to house the inside plant equipment for multiple telephone exchange areas. In North America, the term ''wire center'' may be used to denote a central office location, indicating a facility that provides a telephone with a dial tone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BT Group
BT Group plc (formerly British Telecom) is a British Multinational corporation, multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, Internet access, broadband and Mobile telephony, mobile services in the UK, and also provides subscription television and Information technology, IT services. BT's origins date back to the founding in 1846 of the Electric Telegraph Company, the world's first public telegraph company, which developed a nationwide communications network. BT Group as it came to be started in 1912, when the General Post Office, a government department, took over the system of the National Telephone Company becoming the monopoly telecoms supplier in the United Kingdom. The Post Office Act of 1969 led to the GPO becoming a public corporation, Post Office Telecommunications. The ''British Telecom'' brand was introduced in 1980, and became independent of the R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Service Code
A vertical service code (VSC) is a sequence of digits and the signals star () and pound/hash () dialed on a telephone keypad or rotary dial to access certain telephone service features. Some vertical service codes require dialing of a telephone number after the code sequence. On a touch tone telephone, the codes are usually initiated with the star key, resulting in the commonly used name ''star codes''. On rotary dial telephones, the star is replaced by dialing ''11''. In North American telephony, VSCs were developed by the American Telephone and Telegraph Company (AT&T) as Custom Local Area Signaling Services (CLASS or LASS) codes in the 1960s and 70s. Their use became ubiquitous throughout the 1990s and eventually became a recognized standard. As ''CLASS'' was an AT&T trademark, the term ''vertical service code'' was adopted by the North American Numbering Plan Administration. The use of ''vertical'' is a somewhat dated reference to older switching methods and the fact that t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omega
Omega (, ; uppercase Ω, lowercase ω; Ancient Greek ὦ, later ὦ μέγα, Modern Greek ωμέγα) is the twenty-fourth and last letter in the Greek alphabet. In the Greek numerals, Greek numeric system/isopsephy (gematria), it has a value of 800. The word literally means "great O" (''o mega'', mega meaning "great"), as opposed to omicron, which means "little O" (''o mikron'', mikron meaning "little"). In Phonetics, phonetic terms, the Ancient Greek Ω represented a vowel length, long open-mid back rounded vowel , comparable to the "aw" of the English language, English word ''raw'' in dialects without the cot–caught merger, in contrast to omicron, which represented the close-mid back rounded vowel , and the digraph (orthography), digraph ''ου'', which represented the vowel length, long close-mid back rounded vowel . In Modern Greek, both omega and omicron represent the mid back rounded vowel or . The letter omega is transliteration, transliterated into a Lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha
Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ox'. Letters that arose from alpha include the Latin letter and the Cyrillic letter . Uses Greek In Ancient Greek, alpha was pronounced and could be either phonemically long ( ː or short ( . Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: . * = ' "a time" * = ' "tongue" In Modern Greek, vowel length has been lost, and all instances of alpha simply represent the open front unrounded vowel . In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (), and either of two breathing marks (), as well as combinations of these. It can also combine with the iota subscript (). Greek grammar In the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
