Telephone automatic redial system

Claim 1

An automatic redialing system for telephones comprising a call progress decoder for detecting and generating signals in response to a dial tone and a busy tone on the telephone line, a redial memory capable of generating a dial pulse signal corresponding to the called number stored therein, and logic circuitry connecting said call progress decoder and said redial memory, said circuitry comprising a redial initiation circuit responsive to a dial tone output signal from the call progress decoder for signaling the redial memory to initiate a dial pulse signal, and a redial interrupt circuit responsive to a busy tone signal from the call progress decoder for signaling an interruption to the redialing sequence, said redial interrupt circuit including timing means for temporarily interrupting the dialing sequence for predetermined periods of time between redials and counter means for interrupting the redialing sequence after said called number has been redialed a predetermined number of times, said redial interrupt circuit further comprising an OR gate receiving input from the busy tone signal outputted from said call progress decoder and from said timer means, the output of said OR gate being connected to the input of a NOR gate, the other input of said NOR gate being connected to said counting means, the output of said NOR gate being employed to interrupt said redial sequence.