Abstract: A system for deterring fraudulent cloning by a reader station of valid call-origination message parameters assigned to authorized mobile radiotelephone stations operating within a cell or other area of a cellular radiotelephone system in which valid call origination messages are initiated between the mobile stations and a fixed cell-site radiotransceiver station for that cell or area. A database containing a plurality of valid call-origination message parameter combinations assigned to the authorized mobile stations is established in the radiotelephone system. An auxiliary fraud-deterrent transmitter station transmits call origination messages containing invalid parameters in such cell or area the cellular radiotelephone system. These invalid parameters are not verifiable at the database. The reader station receives both the valid and invalid call origination messages with an inability to discern with certainty between the valid and the invalid call origination messages.