Abstract: A facility for blocking telephone calls is described. The facility is implemented by a telecommunications system that manages assigned and unassigned telephone numbers. The facility determines that a call originator has made two telephone calls to two different unassigned telephone numbers. The facility adds the call originator to a blacklist for a default time period. If the call originator calls any managed telephone number during the default time period, the facility renews the default time period. After the default time period expires, if the call originator makes additional telephone calls to other unassigned telephone numbers, the facility adds the call originator to the blacklist for a time period that is increased from the default time period. The facility increases the time period with each additional call to an unassigned telephone number. Accordingly, the time period is a function of the number of unassigned telephone numbers called by the call originator.

Abstract: A facility for blocking telephone calls is described. The facility is implemented by a telecommunications system that manages assigned and unassigned telephone numbers. The facility determines that a call originator has made two telephone calls to two different unassigned telephone numbers. The facility adds the call originator to a blacklist for a default time period. If the call originator calls any managed telephone number during the default time period, the facility renews the default time period. After the default time period expires, if the call originator makes additional telephone calls to other unassigned telephone numbers, the facility adds the call originator to the blacklist for a time period that is increased from the default time period. The facility increases the time period with each additional call to an unassigned telephone number. Accordingly, the time period is a function of the number of unassigned telephone numbers called by the call originator.