An apparatus and method for processing a call in a PTT system where, when an outgoing terminal transmits an invitation message for PTT service or for call setup to a predetermined incoming terminal in a dormant state, the outgoing terminal transmits the invitation message together with address information on the incoming terminal to enable a PTT server to detect the location of the incoming terminal before the invitation message is transmitted to the incoming terminal, thereby reducing the time taken to set up a PTT call.