TRUNKING METHOD AND APPARATUS FOR ESTABLISHING COMMUNICATION IN A TWO-WAY MOBILE RADIO SYSTEM

A moble radio system is disclosed in which communication is established between at least two user-operable stations over one of a plurality of channels by operating the user-operable stations in accordance with the following steps: (1) When in the receive mode (the push-to-talk switch is open): (i) incrementing the channel selector to select a channel; (ii) determining if a carrier signal is present on the selected channel: (iii) if a carrier signal is not present, returning to step (1) (i); (iv) if a carrier signal is present, determining if the selected trunk identification signal is present on the carrier signal; (v) if the selected trunk identification signal is not present, returning to step (1) (i); and (vi) if the selected trunk identification signal is present on the carrier signal, enabling said transmitter for push-to-talk operation. (2) When in the transmit mode (the push-to-talk switch is closed): (i) if a carrier signal is present on the selected channel, incrementing the channel selector; (ii) if a carrier signal is not present on the selected channel, transmitting a carrier signal with the selected trunk identification signal for a prescribed period of time; (iii) determining whether a carrier signal with the selected trunk identification signal is received on the selected channel; (iv) if a carrier signal with the selected trunk identification signal is not received, returning to step (2) (i); and (v) if a carrier signal with the selected trunk identification signal is received, returning to step (1) (vi).