Abstract: A method and apparatus for reducing the vulnerability of the telecommunications system to unauthorized use that is easy to implement and that can reduce the instances of unauthorized access even during periods when telecommunications personnel are not able to give attention to the traffic on the system. The telecommunications system collects statistics of each user's pattern of telecommunications usage. Typically, these statistics will be in the form of, say, the average number of calls per day or the average number of calls per day on given days of the week. It may also include the mean busy hour for the given days of the week. Moreover, daily averages may be taken not only for all calls but also for all calls of a particular type, e.g., of all international calls. These statistics are taken for a reference period, such as the preceding thirty days, and the corresponding quantity for the current day is also computed.

Abstract: A method and apparatus for reducing the vulnerability of the telecommunications system to unauthorized use that is easy to implement and that can reduce the instances of unauthorized access even during periods when telecommunications personnel are not able to give attention to the traffic on the system. The telecommunications system collects statistics of each user's pattern of telecommunications usage. Typically, these statistics will be in the form of, say, the average number of calls per day or the average number of calls per day on given days of the week. It may also include the mean busy hour for the given days of the week. Moreover, daily averages may be taken not only for all calls but also for all calls of a particular type, e.g., of all international calls. These statistics are taken for a reference period, such as the preceding thirty days, and the corresponding quantity for the current day is also computed.

Abstract: An access-control module (22) is used in connection with a conventional private branch exchange (12) to control direct inward service access (DISA), by which callers calling in on one trunk are afforded access to an outgoing trunk or other destination within the PBX environment. The access-control module (22) is simply plugged into an existing extension, and the PBX (12) initially directs to that extension all calls from the incoming trunk. The access-control module (22) receives the users' authorization code and desired destination and then signals the PBX in the normal manner to transfer the call to an outgoing trunk or other destination within the PBX environment if the incoming call meets certain criteria imposed by the access-control module (22).