Telephone call monitoring apparatus

Claim 1

Telephone call monitoring apparatus for monitoring incoming and outgoing telephone calls from a selected telephone to determine: (1) whether the selected telephone is active or inactive; (2) the telephone numbers of called telephones (3) the durations of completed telephone calls to the selected telephone and the called telephones and (4) to record the telephone number to the called telephones and the durations of the completed calls, in which the selected telephone is connected to a central telephone system by a telephone line in which the selected telephone is capable of generating a series of coded electrical signals on the telephone line to the central telephone system representing a desired called telephone number and wherein the central telephone system, in response to receiving the series of coded electrical signals, generates one or more ring back signals on the telephone line corresponding to ring signals made to the designated called telephone to generate one or more audible rings, wherein the ring back signals have a predetermined frequency, duration and period between individual ring back signals, said apparatus comprising: connecting means operatively connecting the apparatus to the telephone line to receive the signals; status means for determining whether the calling telephone is active or inactive; decoding means responsive to the series of electrical signals representative of the desired called telephone number when the calling telephone is active for decoding the series of electrical signals and generating decoded electrical signals corresponding to the desired called telephone number; ring back signal detection means responsive to the frequency, duration and period between the ring signals for determining when valid ring back signals are generated and then terminated on the line and for generating a telephone answered signal in response thereto; first call duration means responsive to the ring signal detection means and the status means for determining the lapsed time between the generation of the telephone answered signal and the calling telephone become inactive to estimate the duration of the telephone call to the calling telephone; an incoming ring signal detection means for determining when an incoming ring signal is on the line; second call duration means responsive to the incoming ring signal detection means and the status means for determining the lapse time of the selected telephone being active subsequent to the determination that an incoming ring signal is on the line; and recording means operatively connected to the decoding means and the first and second call duration means for recording the telephone numbers of the called telephones and the estimated durations of the completed telephone calls to the called telephones and the selected telephone.