Abstract: A system and method for authenticating a mobile station (MS) in a cellular network. The present invention is an authentication technique that uses the AMPS standard, or a derivative thereof, can authenticate a MS automatically, does not require modifications to the BS, MSC, or VLR, can detect mobile identification number/electronic serial number (MIN/ESN) clones, detects MIN/ESN clones that re-transmit the authentication results of the present invention, and can be easily and inexpensively added to MSs 102 that are based on the AMPS standard (and derivatives thereof). The present invention uses the AMPS-based MSs to automatically execute special authentication procedures using standard MS-to-BS and BS-to-MS messages. The present invention also uses a corresponding network authentication function that can be implemented in either (a) a modified HLR/AC, or (b) a new network component that has access to the signaling information between the HLR and the MSC/VLR.