Push to talk

What is Push to talk?

Push to talk is a software technology for mobile phones that is designed to let you use your phone in real-time direct one-to-one and one-to-many voice communication. The primary technologies behind Push to talk are SIP (Session Initiation Protocol) and IP networks, such as GPRS, or WCDMA.

How does it work?

Push to talk technology channels voice communication through a data network for always-on* functionality. Mobile phones that are equipped with Push to talk software and that have been subscribed to a mobile network's Push to talk communication service can establish a telephone conference with one person or a group of people. Pushing a specific or dedicated button on the mobile phone opens a voice channel to all selected participants, whose phones will automatically play the caller's voice through the phone loudspeaker. Because it is similar to walkie-talkie, Push to talk allows only one participant to talk at a time.

What are the benefits of Push to talk?

* A quick telephone conference with a group of people
* Participants don't have to answer the phone, as the speaker's voice is automatically played through their phones' loudspeakers


Push-to-talk (PTT), also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode.

PTT PoC or Push to Talk over Cellular is a feature similar to walkie-talkie that is provided over a cellular phone network. A typical Push to Talk connection connects almost instantly. One significant advantage of PoC is allowing a single person to reach an active talk group at a button press, thus users no longer need to make several calls to coordinate with a group.

Push-to-talk calls are half duplex communications — while one person speaks, the other(s) listen(s). Traditional mobile phone networks and devices utilize full-duplex communications, allowing customers to call other persons on a mobile or land-line network and be able to simultaneously talk and hear the other party. Such communications require a connection to be started by dialing a phone number and the other party answering the call, and the connection remains active until either party ends the call or the connection is dropped due to signal loss or a network outage. Such a system does not allow for casual transmissions to be sent to other parties on the network without first dialing them up, like is allowed on two-way radios. Full-duplex operation on mobile phone networks is made possible by using separate frequencies for transmission and reception.

Mobile Push-to-Talk service, offered by some mobile carriers, adds functionality for individual half-duplex transmissions to be sent to another party on the system without needing an existing connection to be already established. Since the system is half-duplex (utilizing a single frequency), only one user can transmit by PTT at a time; the other party is unable to transmit until the transmitting user unkeys their PTT button. Currently, PTT service is supported only between parties on the same mobile carrier service, and users with different carriers will be unable to transmit to each other by PTT. However, the advancement of this service will likely bring interconnectivity of PTT traffic between different networks in the near future.