Telephone having reiterative dialing feature

Claim 1

In a telephone having a microphone, a receiver and a hook switch, reiterative dialing means comprising: electrically actuable line seizing means; electrically actuable dialing means including a called number storage register for dialing a desired telephone number; means comprising an automatic gain controlled amplifier, a peak detector and a level comparator for generating energy pulse signals in response to telephone line signals having an amplitude exceeding a predetermined threshold value; means for counting the number of said energy pulse signals occurring in a given time interval and for generating (i) a busy detected signal when said number exceeds a specified value and (ii) a ring detected signal when said number is at least one and no greater than said specified value, said counting means comprising: a multistage shift register having an input terminal, an enable terminal, a reset terminal, at least two lower order output terminals, and a plurality of higher order output terminals; means for coupling said energy pulse signals to said shift register input terminal; means for applying a reset signal to said shift register reset terminal upon generation of any one of said busy detected and ring detected signals, and upon generation of a reiterative mode signal; means for providing an enable signal to said shift register enable terminal a predetermined time period after said dialing means has dialed said desired telephone number; a first OR gate coupled to said lower order output terminals of said shift register; a second OR gate coupled to said higher order output terminals of said shift register; and timing means coupled to the lowest order output terminal of said shift register for enabling the outputs of said first and second OR gates to be coupled to terminals for said ring detected and busy detected signals respectively, for said given time interval, when a signal appears at said lowest order output terminal of said shift register; trigger means responsive to said reiterative mode signal for periodically and repetitively enabling said line seizing means and actuating said dialing means; means responsive to said busy detected signal for disabling said line seizing means; and means responsive to said ring detected signal for generating an alarm signal.