A voice biometric authentication system and method. An authentication system is provided for authenticating a user of a telephonic device, comprising: a setup system for capturing and storing an authentic user voice sample; a comparison system that compares the authentic user voice sample with an inputted voice sample and generates a comparison result; and a control system for controlling access to the telephonic device, wherein the control system: analyzes the comparison result for an initial inputted voice sample received when a telephone call is initiated; and periodically analyzes comparison results for ongoing inputted voice samples received during the telephone call.