In PoC (Push-to-talk over Cellular) participants are organized to a group. By pushing a button on their phone, everyone in the group can hear the talker simultaneously and immediately, without having to hit the answer button.

Key advantages over a standard telephone are a quick call-setup and easy dial. In PoC voice is transferred over data-connection, instead of a legacy circuit-switched channel. Currently PoC systems are deployed in CDMA and GPRS networks.

From the network operator's point of view, PoC is the first IP-based voice service, and as such, the first step towards an all-IP architecture.

PoC service consists of PoC-terminals, server and data network. Although the last letter in the PoC acronym refers to cellular network, PoC also works in fixed networks and WLAN-environments.

Only one person can talk at the time in PoC. When someone wants to talk, s/he presses the button, and, if the channel is free, server grants the channel to the requester. When the user releases the button, the channel is free again. Also, if one holds the channel too long, the server releases it, so others in the group have a chance to talk.

Although voice messaging between groups and individuals is most obvious application for PoC, there are plenty of other services to be offered.

First generation PoC terminals are capable to receive streaming audio and text messages. Examples of new services includes Push-to-NEWS, Push-to-MUSIC and advertisement- sponsored PoC-service.

PoC Application Server creates PoC sessions to real PoC server. From PoC server's point-of-view, these sessions are similar to real PoC sessions created by subscriber's terminal. The VAS-provider feed their content to selected PoC groups. These content is delivered to PoC subscriber's when channel is otherwise idle.

Push-to-* services appears as a member in contact list; once subscribed, service can be switched on/off by single-click, i.e., pressing and immediately releasing the button. This mechanism enables both, subscribed premium VAS-services and promotional VAS-services which are free to subscriber.