Patent ID: 6965297

Claim:
A paging system for providing page messages to radio receiving paging units over a wide area through a plurality of page message transmission systems in which each of said transmission systems is associated with a predefined coverage area in said wide area, said system comprising: a system controller having memory storing a routing database registering each of said paging units with one of said transmission systems, in which said controller routes page messages received by said system to each of said paging units through one of said transmission systems to which the paging unit is registered in accordance with said routing database, wherein the transmission system to which each of the paging units is registered represents the transmission system registered to the paging unit; a plurality of transmission systems, each of said transmission systems being operative for sending page messages received from the system controller to paging units and for sending periodically a system message having at least information which identifies the transmission system to distinguish the transmission system from other transmission systems in the paging system; a plurality of paging units for receiving the system messages of at least one of the transmission systems when located in the associated coverage area of said one transmission system and receiving the page messages from the transmission system registered to the paging unit when the paging unit is located in the coverage area of the transmission system registered to the paging unit, in which one or more of said plurality of paging units are one-way paging units; each of said paging units including a memory storing information representing the current registered transmission system of the paging unit and a respective paging unit controller for determining when the paging unit receives at least one of the system messages sent by one of said transmission systems different from the current transmission system registered to the paging unit; sending means for sending to the system controller at least information identifying the transmission system from said received system message sent by one of said transmission systems different from the current transmission system registered to the paging unit; and said system controller having updating means, responsive to said sending means, for updating the registration of the paging unit in the routing database to one of the transmission systems different from the current transmission system and sending to the paging unit via one of said transmission systems at least information representing the updated transmission system registered to the paging unit.