A method of setting up a Push-To-Talk-over-Cellular (PoC) call between a calling mobile station (MS) and a called MS in a cellular communications network. In GSM/GPRS networks, the method decreases the call setup time, from the time the push-to-talk button is pressed, by causing the called MS to change to READY state before call setup is initiated. This is done by sending a USSD message to the called MS when the calling user selects a PoC contact list on the calling MS. The USSD message causes the called MS to perform a routing area update and change to READY state. This eliminates the need to page the called MS during call setup. In WCDMA networks, the USSD message causes the called MS to reestablish a Radio Resource Control (RRC) connection. The called MS maintains this connection, thereby enabling faster type 2 paging to be utilized for call setup.