Telephone

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A telephone (derived from the τῆλε, tēle, "far" and φωνή, phōnē, "voice", together meaning "distant voice"), 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

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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.
Alexander Graham Bell (March 3, 1847 – August 2, 1922) was a Scottish-born American inventor, scientist, and engineer who is credited with inventing and patenting the first practical telephone.

Telecommunication

telecommunicationscommunicationstelecom
A telephone (derived from the τῆλε, tēle, "far" and φωνή, phōnē, "voice", together meaning "distant voice"), 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.

Mobile phone

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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.

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.

Handset

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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.

Telephone number

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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.

Telephone switchboard

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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.

Technological convergence

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Convergence has given most modern cell phones capabilities far beyond simple voice conversation.
In technological convergence, a cardinal example to convey the concept is that telephones, television, and computers began as separate and mostly unrelated technologies but have converged in many ways into interrelated parts of a telecommunication and media industry underpinned by common elements of digital electronics and software.

Landline

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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.

Rotary dial

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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 counts to decode each digit of the telephone number.
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing.

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.

Push-button telephone

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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.

Signal

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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

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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.

Sidetone

The strong outgoing speech signal from the microphone (transmitter) does not overpower the weaker incoming speaker (receiver) signal with sidetone because a hybrid coil (A3) and other components compensate the imbalance.
In telephony, sidetone is the effect of sound picked up by the telephone's transmitter (mouthpiece) and instantly introduced at a low electronic signal level into the receiver (earpiece) of the same handset, a form of feedback.

Dual-tone multi-frequency signaling

DTMFtouch-tonedual-tone multi-frequency
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 terminating exchange applies an intermittent alternating current (AC) ringing signal of 40 to 90 volts to alert the called party of the incoming call.
Ringing is a telecommunication signal that causes a bell or other device to alert a telephone subscriber to an incoming telephone call.

On- and off-hook

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The landline telephone contains a switchhook (A4) and an alerting device, usually a ringer (A7), that remains connected to the phone line whenever the phone is "on hook" (i.e. the switch (A4) is open), and other components which are connected when the phone is "off hook".

Communications satellite

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

Speakerphone

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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.

Lineman's handset

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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.

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.

Impedance matching

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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.

Pulse dialing

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A rotary-dial telephone uses pulse dialing, sending electrical pulses, that the exchange counts to decode each digit of the telephone number.
Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.

Johann Philipp Reis

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Johann Philipp Reis used the term in reference to his invention, commonly known as the Reis telephone, in c. 1860.
In 1861, he constructed the first make-and-break telephone, today called the Reis telephone.