Push-to-talk (PTT or P2T) is also alternately known as Press-to-Transmit. PTT is a means of communication in half-duplex mode. When using a 2-way radio, the device can either transmit or receive a signal, but transmitting and receiving cannot happen at the same time. This is possible by the use of a switch wherein on pressing the switch the device activates the transmitter and changes from the receiving mode to transmitting mode. In half duplex mode, since the users can only either transmit or receive at any point of time, each party must wait for their turn to speak.
One variation of the PTT is the Push to Talk over Cellular (PoC). Cellular phones service providers can provide this service which allows the user to use their phone as a walkie-talkie with unlimited range.