Portal:Telephones

Direct distance dialing (DDD) is a telecommunications service feature in North America by which a caller may, without operator assistance, call any other user outside the local calling area. Direct dialing by subscribers typically requires extra digits to be dialed as prefixes to the directory telephone number of the destination. International Direct Distance Dialing (IDDD) extends the system beyond the geographic boundaries of the North American Numbering Plan (NANP). (Full article...)

An emergency telephone is a public telephone provided for making calls to emergency services. (Full article...)

Multi-frequency dialing

These multi-frequency tones were generated by automated switching equipment. The blue box was designed to replicate these tones.

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A blue box is an electronic device that produces tones used to generate the in-band signaling tones formerly used within the North American long-distance telephone network to send line status and called number information over voice circuits. During that period, charges associated with long-distance calling were commonplace and could be significant, depending on the time, duration and destination of the call. A blue box device allowed for circumventing these charges by enabling an illicit user, referred to as a "phreaker," to place long-distance calls, without using the network's user facilities, that would be billed to another number or dismissed entirely by the telecom company's billing system as an incomplete call. A number of similar "color boxes" were also created to control other aspects of the phone network. (Full article...)

Edison, c. 1922

Thomas Alva Edison (February 11, 1847 – October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, which include the phonograph, the motion picture camera, and early versions of the electric light bulb, have had a widespread impact on the modern industrialized world. He was one of the first inventors to apply the principles of organized science and teamwork to the process of invention, working with many researchers and employees. He established the first industrial research laboratory.

Edison was raised in the American Midwest. Early in his career he worked as a telegraph operator, which inspired some of his earliest inventions. In 1876, he established his first laboratory facility in Menlo Park, New Jersey, where many of his early inventions were developed. He later established a botanical laboratory in Fort Myers, Florida, in collaboration with businessmen Henry Ford and Harvey S. Firestone, and a laboratory in West Orange, New Jersey, that featured the world's first film studio, the Black Maria. With 1,093 US patents in his name, as well as patents in other countries, Edison is regarded as the most prolific inventor in American history. Edison married twice and fathered six children. He died in 1931 due to complications from diabetes. (Full article...)