Abstract: A telephone caller screening device is operable with a pre-existing telephone line with an existing installed telephone device. In one mode, the telephone caller screening device selects and stores caller ID information from incoming telephone calls for later use to compare with caller entered identification data to determine whether the premise telephone user should be alerted to the incoming telephone call. In a second mode the telephone caller screening device controls the telephone system by generating an off-hook condition on the pre-existing telephone line to suppress the ring signal from an incoming telephone call to prevent audible ringing of the telephone device. The telephone caller screening device generates an alerting signal in an alerting device when the caller entered identification data compares with a stored caller identification data.

Abstract: A telephone ring signal detector is coupled to a telecommunication line for detecting a first telephone ring signal, and for discriminating the first telephone ring signal from other line signals on the line. This detector comprises an event generator, coupled to the line, for receiving an incoming signal and for generating an initial event signal and an ending event signal, and a signal characteristic generator, coupled to the line and to the event generator, for generating a signal characteristic of the incoming signal after the initial event signal. This detector further comprises a signal characteristic limit device, for generating a predetermined signal characteristic range limit of the first telephone ring signal, and a signal characteristic comparator coupled to the signal characteristic generator, to the signal characteristic limit device and to the event generator, for comparing the signal characteristic with the predetermined signal characteristic range limit.