Telephone exchange — A telephone operator manually connecting calls with cord pairs at a telephone switchboard. In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls. A central… … Wikipedia
Business telephone system — Early model 464G Western Electric key telephone set A business telephone system is any of a range of a multiline telephone systems typically used in business environments, encompassing systems ranging from small key systems to large scale private … Wikipedia
Private branch exchange — A private branch exchange (PBX) is a telephone exchange that serves a particular business or office, as opposed to one that a common carrier or telephone company operates for many businesses or for the general public. PBXs are also referred to as … Wikipedia
Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… … Universalium
Signed graph — In the area of graph theory in mathematics, a signed graph is a graph in which each edge has a positive or negative sign.Formally, a signed graph Sigma; is a pair ( G , sigma;) that consists of a graph G = ( V , E ) and a sign mapping or… … Wikipedia
Life Sciences — ▪ 2009 Introduction Zoology In 2008 several zoological studies provided new insights into how species life history traits (such as the timing of reproduction or the length of life of adult individuals) are derived in part as responses to… … Universalium
Automatic number identification — (ANI) is a feature of telephony intelligent network services that permits subscribers to display or capture the telephone numbers of calling parties. In the United States it is part of Inward Wide Area Telephone Service (WATS). The ANI service… … Wikipedia
Fictitious force — Classical mechanics Newton s Second Law History of classical mechanics … Wikipedia
Accelerated reference frame — In theoretical physics, an accelerated reference frame is usually a coordinate system or frame of reference, that undergoes a constant and continual change in velocity over time as judged from an inertial frame. An object in an accelerated frame… … Wikipedia
United Kingdom — a kingdom in NW Europe, consisting of Great Britain and Northern Ireland: formerly comprising Great Britain and Ireland 1801 1922. 58,610,182; 94,242 sq. mi. (244,100 sq. km). Cap.: London. Abbr.: U.K. Official name, United Kingdom of Great… … Universalium
Integrated Services Digital Network — ISDN redirects here. For other uses, see ISDN (disambiguation). Integrated Services Digital Network (ISDN) is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the… … Wikipedia