A cellular telecommunications system having a security feature which allows only pre-authorized users to complete cellular telephone calls. The system and method recognizes a cellular radiotelephone's pre-programmed a pre-selected telephone number and a automated number identification code (ANI). The pre-selected telephone number is reserved to the pre-paid cellular telecommunications system. The cellular radiotelephone transmits the ANI and a dialed number identification system code (DNIS) to a cellular switch, which contacts a host computer for call validation by the pre-paid service provider.