Push to talk
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Push-to-talk (PTT), also known as press-to-transmit, is a method of having conversations or talking on
half-duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...
communication lines, including
two-way radio A two-way radio is a radio that can both transmit and receive radio waves (a transceiver), unlike a broadcast receiver which only receives content. It is an audio (sound) transceiver, a transmitter and receiver in one unit, used for bidirecti ...
, using a momentary button to switch from voice reception mode to transmit mode.


History

For example, an
air traffic controller Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control ...
usually supervises several aircraft and talks on one radio frequency to all of them. Those under the same frequency can hear others' transmissions while using
procedure word Procedure words (abbreviated to prowords) are words or phrases limited to radio telephone procedure used to facilitate communication by conveying information in a condensed standard verbal format. Prowords are voice versions of the much older pro ...
s such as "break", "break break" to separate order during the conversation (ICAO doc 9432). In doing so, they are aware of each other's actions and intentions. Unlike in a
conference call A conference call is a telephone call in which someone talks to several people at the same time. The conference call may be designed to allow the called party to participate during the call or set up so that the called party merely listens into ...
, they do not hear background noise from the ones who are not speaking. Similar considerations apply to
police radio Police radio is a radio system used by police and other law enforcement agencies to communicate with one another. Police radio systems almost always use two-way radio systems to allow for communications between police officers and dispatchers. ...
, the use of
business band In the United States, the business band is the colloquial name used by radio users who utilize, and scanner hobbyists who listen to, the Federal Communications Commission (FCC) Industrial/Business pool frequencies. The regulations listing frequen ...
radios on
construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...
sites, and other scenarios requiring coordination of several parties.
Citizens Band Citizens band radio (also known as CB radio), used in many countries, is a land mobile radio system, a system allowing short-distance person-to-many persons bidirectional voice communication among individuals, using two way radios operating on ...
is another example of classic push-to-talk operation. The PTT switch is most commonly located on the radio's handheld microphone, or for small hand-held radios, directly on the radio. For heavy radio users, a PTT foot switch may be used, and also can be combined with either a boom-mounted microphone or a headset with integrated microphone. Less commonly, a separate hand-held PTT switch may be used. This type of switch was historically called a ''pressel''. In situations where a user may be too busy to handle a talk switch,
voice operated switch In telecommunications, a voice operated switch, also known as VOX or voice-operated exchange, is a switch that operates when sound over a certain threshold is detected. It is usually used to turn on a transmitter or recorder when someone speaks and ...
es are sometimes employed. Some systems use
PTT ID PTT ID, or Push-To-Talk ID, is a generic term for an automatic number identification (ANI)-like system used in two-way radio systems. It provides identification of the transmitting radio over the air, and is commonly used in selective calling/sign ...
to identify the speaker. Manufacturers now make units specifically designed for ''PTT over cellular'' (POC or PoC).


Mobile phones

''Push-to-talk over cellular'' (PoC) is a service option for a
cellular phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket 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 ...
network that enables subscribers to use their phones as
walkie-talkies A walkie-talkie, more formally known as a handheld transceiver (HT), is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald Hings, radio engineer Alfred J. Gross, ...
with unlimited range. A typical push-to-talk connection connects almost instantly. A significant advantage of PTT is the ability for a single person to reach an active talk group with a single button press; users don't need to make several
telephone call A telephone call is a connection over a telephone network A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and interne ...
s to coordinate with a group. Push-to-talk cellular calls similarly provide half-duplex communications — while one person transmits, the other(s) receive. This combines the operational advantages of PTT with the interference resistance and other virtues of mobile phones.


Current use in mobile telephony

Mobile push-to-talk services, offered by some mobile carriers directly as well as by independent companies, adds PTT functionality to smartphones and specialized mobile handsets (hand portable and mobile/base station PTT Radio Terminals). In addition to mobile handsets, some services also work on a laptop, desktop, and tablet computers.


Smartphone and computer apps

Recent development in PTT communications is the appearance of apps on
smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
s, some of which can function on multiple platforms. Wireless carrier-grade PTT systems have adapted to and adopted the smartphone platform by providing downloadable apps that support their PTT systems across many mobile platforms. Over-the-top (OTT) applications are not dependent on a specific carrier and nearly as fast as carrier implementations.


See also

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References


Push-to-Talk over Cellular Consortium Phase 2 Specifications and DocumentationOpen Mobile Alliance - Push to talk over Cellular (PoC) - Architecture Candidate Version 2.0 – 26 February 2008
{{DEFAULTSORT:Push-To-Talk IMS services