A method of identifying fraud in a telecommunications system, the method including receiving data related to a current call placed from an originating ANI to a terminating ANI, where the received data includes the terminating ANI and a billing number used to place the call. Billing numbers for prior calls to the terminating ANI, if any, and corresponding indicia of the times of the calls are retrieved. A determination is made of whether the number of billing numbers used for the current and prior calls to the terminating ANI over a prior period of time falling within a time interval satisfies a threshold. If the threshold is satisfied, a fraud alert is generated.