Push-to-talk Over Cellular (PoC) is very similar to the well known walkie-talkie communication service. It provides a one-to-one or one-to-many speech service to a group of people in half-duplex mode, which means that only one participant can talk at a given time, while the others are listening. Like traditional walkie-talkie services, a session participant requests the floor by pressing a ‘talk button’ on its terminal. As the participant stops talking, he releases the talk button, allowing another participant to request the speech channel.
However, there are some basic differences with analogue or digital low-cost solutions which everyone can buy and easily deploy, due to the fact that PoC is not only supported by the terminal, but also relies on a full network infrastructure. The added value of PoC can be summarized by the two following points: