Telephone

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A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly.wikipedia
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Alexander Graham Bell

BellGraham BellBell, Alexander Graham
In 1876, Scottish emigrant 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. Charles Bourseul, Antonio Meucci, Johann Philipp Reis, Alexander Graham Bell, and Elisha Gray, amongst others, have all been credited with the invention of the telephone.
Alexander Graham Bell ('Graham' pronounced ) (March 3, 1847 – August 2, 1922) was a Scottish-born scientist, inventor, engineer, and innovator who is credited with inventing and patenting the first practical telephone.

Mobile phone

cell phonemobilemobile phones
Hand-held mobile phones were introduced for personal service starting in 1973.
A mobile phone, cell phone, cellphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, 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.

Telecommunication

telecommunicationscommunicationstelecom
A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly.
20th- and 21st-century technologies for long-distance communication usually involve electrical and electromagnetic technologies, such as telegraph, telephone, and teleprinter, networks, radio, microwave transmission, fiber optics, and communications satellites.

Landline

fixed linefixed-lineland line
This gave rise to landline telephone service in which each telephone is connected by a pair of dedicated wires to a local central office switching system, which developed into fully automated systems starting in the early 1900s, and eventually into a worldwide public switched telephone network. A traditional landline telephone system, also known as plain old telephone service (POTS), commonly carries both control and audio signals on the same twisted pair (C in diagram) of insulated wires, the telephone line.
A landline telephone (also known as land line, land-line, main line, home phone, landline, fixed-line, and wireline) is a phone that uses a metal wire or optical fiber telephone line for transmission as distinguished from a mobile cellular line, which uses radio waves for transmission.

Duplex (telecommunications)

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Telephones are duplex devices, meaning they permit transmission in both directions simultaneously.
An example of a full-duplex device is a telephone; the parties at both ends of a call can speak and be heard by the other party simultaneously.

Telephone switchboard

switchboardswitchboardscentral switchboard
Being impractical beyond just a few customers, these systems were quickly replaced by manually operated centrally located switchboards.
A telephone switchboard is a telecommunications system used in the public switched telephone network or in enterprises to interconnect circuits of telephones to establish telephone calls between the subscribers or users, or between other exchanges.

Handset

telephone handsethandset receiverphone receivers
The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation.
A handset is a component of a telephone that a user holds to the ear and mouth to receive audio through the receiver and speak to the remote party via the built-in transmitter.

Rotary dial

dialrotary telephonerotary phone
Until the 1960s dials used almost exclusively the rotary technology, which was replaced by dual-tone multi-frequency signaling (DTMF) with pushbutton telephones (A4). A rotary-dial telephone uses pulse dialing, sending electrical pulses, that the exchange can count to get the telephone number (as of 2010 many exchanges were still equipped to handle pulse dialing).
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing.

Telephone number

phone numbertelephone numbersphone numbers
In addition, most telephones contain a ringer to announce an incoming telephone call, and a dial or keypad to enter a telephone number when initiating a call to another telephone.
In addition to telephones, they have been used to access other devices, such as computer modems, pagers, and fax machines.

Push-button telephone

10- or 12-button touch-tone telephonespush-buttonpush-button dialing
Until the 1960s dials used almost exclusively the rotary technology, which was replaced by dual-tone multi-frequency signaling (DTMF) with pushbutton telephones (A4).
The push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to having a rotary dial as in earlier telephone instruments.

Plain old telephone service

POTSLocal Telephone Servicetelephone
A traditional landline telephone system, also known as plain old telephone service (POTS), commonly carries both control and audio signals on the same twisted pair (C in diagram) of insulated wires, the telephone line.
Plain old telephone service (POTS), or plain ordinary telephone service, is a retronym for voice-grade telephone service employing analog signal transmission over copper loops.

Dual-tone multi-frequency signaling

DTMFtouch-tonetouch tone
Until the 1960s dials used almost exclusively the rotary technology, which was replaced by dual-tone multi-frequency signaling (DTMF) with pushbutton telephones (A4).
Dual-tone multi-frequency signaling (DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers.

Ringing (telephony)

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If the called party's line is available, the exchange sends an intermittent ringing signal (about 75 volts alternating current (AC) in North America and UK and 60 volts in Germany) to alert the called party to an incoming call.
Ringing is a telecommunication signal that causes a bell or other device to alert a telephone subscriber to an incoming telephone call.

Communications satellite

satellitesatellite communicationscommunication satellite
Satellite technology may be used for communication over very long distances.
Communications satellites are used for television, telephone, radio, internet, and military applications.

Signal

signalselectrical signalelectrical signals
The transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker.
For example, the words "Mary had a little lamb" might be the message spoken into a telephone.

Twisted pair

twisted-pairunshielded twisted pairshielded twisted pair
A traditional landline telephone system, also known as plain old telephone service (POTS), commonly carries both control and audio signals on the same twisted pair (C in diagram) of insulated wires, the telephone line.
UTP is the primary wire type for telephone usage and is very common for computer networking.

Lineman's handset

test set
A lineman's handset is a telephone designed for testing the telephone network, and may be attached directly to aerial lines and other infrastructure components.
A lineman's handset is a special type of telephone used by technicians for installing and testing local loop telephone lines.

Speakerphone

speaker
In most landline telephones, the transmitter and receiver (microphone and speaker) are located in the handset, although in a speakerphone these components may be located in the base or in a separate enclosure.
A speakerphone is a telephone with a microphone and loudspeaker provided separately from those in the handset.

Johann Philipp Reis

Johann-Philipp-Reis AwardJohann ReisPhilip Reis
Later, c. 1860, Johann Philipp Reis used the term in reference to his Reis telephone, his device appears to be the first such device based on conversion of sound into electrical impulses, the term telephone was adopted into the vocabulary of many languages. Charles Bourseul, Antonio Meucci, Johann Philipp Reis, Alexander Graham Bell, and Elisha Gray, amongst others, have all been credited with the invention of the telephone.
In 1861, he constructed the first make-and-break telephone, today called the Reis telephone.

Fiber-optic communication

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In modern telephone networks, fiber-optic cable and digital technology are often employed in such connections.
On June 3, 1880, Bell conducted the world's first wireless telephone transmission between two buildings, some 213 meters apart.

Microphone

microphonescondenser microphonedynamic microphone
The essential elements of a telephone are a microphone (transmitter) to speak into and an earphone (receiver) which reproduces the voice in a distant location.
Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, radio and television broadcasting, and in computers for recording voice, speech recognition, VoIP, and for non-acoustic purposes such as ultrasonic sensors or knock sensors.

Charles Bourseul

Bourseul, Charles
Charles Bourseul, Antonio Meucci, Johann Philipp Reis, Alexander Graham Bell, and Elisha Gray, amongst others, have all been credited with the invention of the telephone.
Charles Bourseul (28 April 1829 – 23 November 1912) was a pioneer in development of the "make and break" telephone about 20 years before Bell made a practical telephone.

Reis telephone

make-and-break transmittertelephone
Later, c. 1860, Johann Philipp Reis used the term in reference to his Reis telephone, his device appears to be the first such device based on conversion of sound into electrical impulses, the term telephone was adopted into the vocabulary of many languages.
The Reis telephone was an invention named after Philipp Reis of a telephonelike device he constructed.

Pulse dialing

dial pulsepulse diallingpulse dial
A rotary-dial telephone uses pulse dialing, sending electrical pulses, that the exchange can count to get the telephone number (as of 2010 many exchanges were still equipped to handle pulse dialing).
Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.

Impedance matching

matching networkimpedance matchmatching
The junction box (B) arrests lightning (B2) and adjusts the line's resistance (B1) to maximize the signal power for the line length.
In older audio systems (reliant on transformers and passive filter networks, and based on the telephone system), the source and load resistances were matched at 600 ohms.