SIGNALLING METHOD FOR ESTABLISHING TRUNKED COMMUNICATION

SIGNALLING METHOD FOR ESTABLISHING TRUNKED COMMUNICATION Abstract A trunked communication signalling method is provided by a unifying signalling protocol in which subscribers (102, 104) request communication channels (106) using only their individual IDs (404) encoded into single ISWs (402). The central (110) decodes the call reguest, extracts the requesting subscriber's individual ID, which is cross referenced to determine the subscriber's talk-group affiliation(s). If the requesting subscriber's affiliation(s) are not known, the central commands the subscriber to transmit its affiliation using dual ISW signalling (408). In another aspect of the present invention, each subscriber automatically informs the central of a change in talk-group affiliation, thereby providing continual affiliation updates. In this way, many thousand subscribers are afforded access to a single trunked system (100), and control channel traffic congestion is minimized.