Performing human client verification over a voice interface

Abstract

Methods and apparatus, including computer program products, implementing and using techniques for verifying incoming telephone calls to a telephone services subscriber. An incoming telephone call from a caller is received. A time variable including one or more of a current date, a day-of-week, and a time-of-day is determined. One or more challenge questions is selected from a pre-defined schedule, in response to determining the time variable. The schedule includes challenge questions for different time variables. The caller is subjected to the one or more challenge questions. At least one challenge response to one or more of the selected challenge questions is received. It is determined whether the at least one challenge response was an expected correct response. If the at least one challenge response was correct, an action is taken with respect to the incoming telephone call.