Abstract: A system for reducing fraudulent use of a mobile telephone number in a radio telecommunications network. The system automatically bars call originations from the mobile telephone if the mobile telephone does not register with the network for a predetermined time period, or if the mobile telephone does not originate a call for a second predetermined time period. The system determines when a mobile telephone originates a call, measures a predetermined time period with a timing mechanism, and starts the timing mechanism when the mobile telephone originates a first call. The system then determines whether a second call originated from the mobile telephone during the predetermined time period and restarts the timing mechanism at the time that the mobile telephone originates a second call upon determining that the second call originated from the mobile telephone during the predetermined time period.