Abstract: A method and apparatus for controlling responses from mobile communication devices in a two-way radio communication system are provided. An infrastructure provides a multicast transmission, for transmission in a first time interval to members of a group of mobile communication devices. The infrastructure assigns a second time interval for at least a subgroup of the members to transmit to the infrastructure with reserved access, and assigns the reserved access timeslots. The infrastructure also assigns a third time interval, for members of the group to transmit to the infrastructure using random access. The second and third time intervals may be separated by other signaling, such as re-transmission by the infrastructure of parts of the multicast transmission. The selection and setting of time intervals may be based on information provided by a transmitter. A mobile communication device is also provided.