Portal:Telephones

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The Telephones Portal

A rotary dial telephone, c. 1940s

A telephone is a telecommunications device that permits 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 Greek: τῆλε (tēle, far) and φωνή (phōnē, voice), together meaning distant voice. A common short form of the term is phone, which came into use early in the telephone's history.

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. (Full article...)

The Samsung Galaxy Z series are foldable smartphones

A mobile phone (or cellphone) is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area, as opposed to a fixed-location phone (landline phone). The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture, and therefore mobile telephones are called cellphones (or "cell phones") in North America. In addition to telephony, digital mobile phones support a variety of other services, such as text messaging, multimedia messaging, email, Internet access (via LTE, 5G NR or Wi-Fi), short-range wireless communications (infrared, Bluetooth), satellite access (navigation, messaging connectivity), business applications, payments (via NFC), multimedia playback and streaming (radio, television), digital photography, and video games. Mobile phones offering only basic capabilities are known as feature phones (slang: "dumbphones"); mobile phones that offer greatly advanced computing capabilities are referred to as smartphones. (Full article...)

A smartphone (often simply called a phone) is a mobile device that combines the functionality of a traditional mobile phone with advanced computing capabilities. It typically has a touchscreen interface, allowing users to access a wide range of applications and services, such as web browsing, email, and social media, as well as multimedia playback and streaming. Smartphones have built-in cameras, GPS navigation, and support for various communication methods, including voice calls, text messaging, and internet-based messaging apps. (Full article...)

A blue phone handset icon lying horizontally in the center of the image with a reddish-orange arrow, the head at the left, bouncing diagonally off the top
A missed-call icon

A missed call is a telephone call that is deliberately terminated by the caller before being answered by its intended recipient, in order to communicate a pre-agreed message. It is a form of one-bit messaging.

Missed calls are common in emerging markets where mobile phones with limited outgoing calls are widely used; as the call is not actually completed and connected, it does not carry a cost to the caller, hence they can conserve their remaining prepaid credit. Specific patterns of consecutive missed calls have been developed in some countries to denote specific messages. Missed calls are also referred to in some parts of Africa as beeping, flashing in Nigeria, a flashcall in Pakistan, miskol in the Philippines and ring-cut in Sri Lanka.

Missed calls are especially prominent in India. Expanding upon their use as a communications method, they have been adopted as a form of marketing communications, in which users can "missed call" specific numbers and receive a call or text back that contains advertising and other content. Other forms of services have also been built around use of missed calls in such a manner, primarily to take advantage of the fact that feature phones are still relatively common in India as opposed to smartphones. (Full article...)
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modified TA-312 field telephone

Field telephones are telephones used for military communications. They can draw power from their own battery, from a telephone exchange (via a central battery known as CB), or from an external power source. Some need no battery, being sound-powered telephones.

Field telephones replaced flag signals and the telegraph as an efficient means of communication. The first field telephones had a battery to power the voice transmission, a hand-cranked generator to signal another field telephone or a manually-operated telephone exchange, and an electromagnetic ringer which sounded when current from a remote generator arrived. This technology was used from the 1910s to the 1980s. Later the ring signal was operated by a pushbutton or automatically as on domestic telephones. Manual systems are still widely used, and are often compatible with the older equipment.

Shortly after the invention of the telephone, attempts were made to adapt the technology for military use. Telephones were already being used to support military campaigns in British India and in British colonies in Africa in the late 1870s and early 1880s. In the United States telephone lines connected fortresses with each other and with army headquarters. They were also used for fire control at fixed coastal defence installations. The first telephone for use in the field was developed in the United States in 1889 but it was too expensive for mass production. Subsequent developments in several countries made the field telephone more practicable. The wire material was changed from iron to copper, devices for laying wire in the field were developed and systems with both battery-operated sets for command posts and hand generator sets for use in the field were developed. The first purposely-designed field telephones were used by the British in the Second Boer War. They were used more extensively in the Russo-Japanese War, where all infantry regiments and artillery divisions on both sides were equipped with telephone sets. By the First World War the use of field telephones was widespread, and a start was made at intercepting them. (Full article...)

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Ringing tone (audible ringing, also ringback tone) is a signaling tone in telecommunication that is heard by the originator of a telephone call while the destination terminal is alerting the receiving party. The tone is typically a repeated cadence similar to a traditional power ringing signal (ringtone), but is usually not played synchronously. Various telecommunication groups, such as the Bell System and the General Post Office (GPO) developed standards, in part taken over by the European Telecommunications Standards Institute (ETSI) and other standards bodies. With modern cell phone and smartphone technology ringing tone can be customized and even used for advertising. (Full article...)

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Draper at Maker Faire Berlin, 2015
John Thomas Draper (born March 11, 1943), also known as Captain Crunch, Crunch, or Crunchman (after the Cap'n Crunch breakfast cereal mascot), is an American computer programmer and former phone phreak. He is a widely known figure within the computer programming world and the hacker and security community, and generally lives a nomadic lifestyle. (Full article...)

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