Portal:Telephones

Fax (short for facsimile), sometimes called telecopying or telefax (short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer or other output device. The original document is scanned with a fax machine (or a telecopier), which processes the contents (text or images) as a single fixed graphic image, converting it into a bitmap, and then transmitting it through the telephone system in the form of audio-frequency tones. The receiving fax machine interprets the tones and reconstructs the image, printing a paper copy. Early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines transmit an audio-encoded digital representation of the page, using data compression to transmit areas that are all-white or all-black, more quickly.

Initially a niche product, fax machines became ubiquitous in offices in the 1980s and 1990s. However, they have largely been rendered obsolete by Internet-based technologies such as email and the World Wide Web, but are still used in some medical administration and law enforcement settings. (Full article...)

A modular smartphone is a smartphone designed for users to upgrade or replace components and modules without the need for resoldering or repair services. The most important component is the main board, to which others such as cameras and batteries are attached. Components can be obtained from open-source hardware stores.

This design aims to reduce electronic waste, increase the phone's lifespan, and lower repair costs. However, modular smartphones are generally bulkier and slower than their non-modular counterparts which may make them less attractive for most consumers. (Full article...)

A disconnect tone in telephony is a tone provided to the remaining party to a call after the remote party hangs up. Typically, the disconnect tone is a few cycles of the reorder, busy, or the off-hook tone (e.g. in US), or between five and fifteen seconds of the Number Unobtainable tone (e.g. in UK). (Full article...)

Bell, c. 1895

Alexander Graham Bell (/ˈɡreɪ.əm/ ^ⓘ; born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born Canadian-American inventor, scientist, and engineer who is credited with patenting the first practical telephone. He also co-founded the American Telephone and Telegraph Company (AT&T) in 1885.

Bell's father, grandfather, and brother had all been associated with work on elocution and speech, and both his mother and wife were deaf, profoundly influencing Bell's life's work. His research on hearing and speech further led him to experiment with hearing devices, which eventually culminated in his being awarded the first U.S. patent for the telephone, on March 7, 1876. Bell considered his invention an intrusion on his real work as a scientist and refused to have a telephone in his study.

Many other inventions marked Bell's later life, including ground-breaking work in optical telecommunications, hydrofoils, and aeronautics. Bell also had a strong influence on the National Geographic Society and its magazine while serving as its second president from 1898 to 1903. (Full article...)