A plurality of central stations generate and transmit control signals that are received by individual remote stations. Ordinarily, each remote station is assigned to a specific central station. The control signals include a first part that includes identifying information for one or more intended receiving stations, and a second part that includes control signals for the intended receiving station or stations. The remote stations shift operation between a first and second operating mode. In the first mode, they receive the control signals from the central station to which they are assigned, and in the second mode, they do not. For a period of time that is substantially coincident with the first part of the control signals, the remote stations operate in the first operating mode to determine whether the subsequent messages are intended for them. If they are, the remote stations continue to operate in this mode. Otherwise, the remote stations begin operating in the second mode for the duration of the control signal transmission.