Embodiments include a trunking site base station receiving a first base station control packet over a network and, in response, transmitting a first subscriber control packet over a subscriber control channel at a first transmission time that is determined based on a transmission schedule. The first subscriber control packet includes a frame sync, a network ID, and a payload. Responsive to determining that a second base station control packet has not been received before a first timeout (or based on another trigger), the base station transmits a second subscriber control packet at a second transmission time that is determined based on the transmission schedule. The second subscriber control packet includes the frame sync and the network ID. The second subscriber control packet also may include a payload indicating a delay period for a subscriber radio to wait before making an attempt to register with a different trunking site.