A service that turns smartphones into walkie-talkies but without distance limitations because it uses the cellular system. Also called "push over cellular" (PoC) and "push to talk over cellular" (PTToC), Nextel popularized the service. Today, AT&T, Verizon and T-Mobile offer push-to-talk service under their own banner as well as third parties.
In work environments, where people are separated by distance but must communicate on a moment's notice or even all day long, push-to-talk is more convenient than making a phone call and waiting for the ringtone to notify the user. As soon as the person hears the sender's voice, the connection is established. Of course, people must have their phones handy.
Half-Duplex
Push-to-talk is one-way communications (to or from but not simultaneous). When in the app, tapping a button puts the device in transmit mode and releasing it enables the other party to speak. See
walkie-talkie.