Abstract: A data communications system covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Messages carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM takes a signal strength measurement every time it receives a message from a portable radio. The GCC includes a multi-tasking processor that executes tasks on a priority basis. Inbound messages are processed on a high priority basis and are ignored if the GCC is overloaded and the inbound message is of the type that will be reasserted. Thus, by shedding inbound messages that will be re-asserted, the GCC can accomodate peak message loads demanding 100% of its capacity without becoming unstable.