Method of communication using push to talk scheme in mobile communication system

A mobile communication terminal for communication with another mobile communication terminal comprising:

• a selecting means for selecting at least one subscriber with whom the calling user wants to communicate with through the Push-to-Talk (PTT) call traffic scheme, and selecting one of a plurality of predetermined importance levels of a PTT call request message;
• a transmitting means for transmitting a PTT call request message having the selected one importance level to a PTT server;
• a receiving means for receiving a PTT call request message from a PTT server;
• and
• an indicating means that provides a predetermined alarm message indicating a reception of the PTT call request message in response to the selected one of the importance levels of the PTT call request message.

A Push-To-Talk (PTT) server for establishing a PTT connection between mobile communication terminals comprising:

• a receiving means for receiving connection requests from a mobile communication terminal and for receiving invite requests when the user of a calling mobile communication terminal has selected a user of a called mobile communication terminal on a buddy list to contact and the level of importance for the selected user;
• a transmitting means for transmitting a connection acknowledgement and a buddy list to a mobile communication terminal in response to a connection request;
• and
• a confirming means for confirming the selected importance level included in the invite message sent by mobile communication terminal, wherein when transmitting the PTT call request message from the calling mobile communication terminal to the called mobile communication terminal, the PTT server confirms the importance level included in the PTT call request message to make a properly weighted charge bill based on the confirmed importance level.