A method and apparatus are described for managing a mass registration scenario in a two-way radio system. A site controller in a trunked radio system detects a mass registration condition in which registration requests by subscriber units are likely to collide on an inbound control channel. During the mass registration condition, the site controller initiates a restriction period by instructing subscriber units that are members of particular talkgroups to temporarily cease registration requests. Those talkgroup members are permitted to resume their registration requests when a predetermined delay time has passed since the members were instructed to cease registration, or when a particular silence time has passed without registration activity over the control channel.