Stop time-out until after first DTMF digit dialed circuit

Details Stop time-out until after first DTMF digit dialed circuit Stop time-out until after first DTMF digit dialed circuit

1974-12-19

1976-06-01

Claffy, Kathleen H.

179 84VF, H04Q 150

Patent

active

039611418

ABSTRACT:
A circuit for preventing the automatic operation of the time-out portion of a tone-to-pulse converter until after the first DTMF digit is dialed is disclosed. When a calling party goes OFF HOOK, the forward loop current flowing in the tip and ring in leads is sensed. The sensed current creates a binary zero signal that sets a latch circuit. The latch circuit inhibits the automatic operation of the time-out portion of the tone-to-pulse converter until the latch circuit is reset. The latch circuit is normally reset by the first output of the tone-to-pulse converter adapted to create a rotary dial-type pulse. Alternatively, going ON HOOK without creating a DTMF digit resets the latch circuit, as does the occurrence of a rotary dial pulse on the tip and ring in leads.

REFERENCES:
patent: 3376391 (1968-04-01), Finkhauser et al.
patent: 3430002 (1969-02-01), Roscoe
patent: 3573663 (1971-04-01), Huge et al.
H. P. Anderson, "Touch-Tone Converter for Step-By-Step PBX's," Bell Laboratories Record, Sept. 1965, pp. 333-336.

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