Rotary dial restriction circuit

Details Rotary dial restriction circuit Rotary dial restriction circuit

1975-06-16

1977-04-26

Claffy, Kathleen H.

179 63R, 179189D, H04M 166

Patent

active

040202950

ABSTRACT:
A telephone station circuit is disclosed with restriction circuitry which allows a noncoin phone to be placed in a public location by preventing the generation of dial pulses on a call from the station except when a dialed number is preceded illustratively by an initial dialed "0." The call is thereby routed to an operator for appropriate charging procedures. The disclosed circuit utilizes an ordinary noncoin rotary dial telephone with a relay which is operated to enable called number dial pulsing from the noncoin phone by a special cam arrangement. The cam arrangement in turn is actuated by the dial mechanism of the phone upon the dialing of an initial 0 digit. The restriction relay is connected in series with the station line and has a pair of normally closed contacts which shunt the dial pulse contacts to prevent normal dialing. When the station goes off-hook, the relay is prevented from operating by a separate pair of contacts, associated with the dial mechanism which contacts shunt the relay coil. The dial contacts are activated by the dial mechanism which is equipped with a pin attached to one of its gear wheels. When the dial is wound into position for dialing a 0, the pin opens the contacts thereby removing the shunt from the relay coil. The relay then operates and removes the shunt from the dial pulse contacts. The relay remains operated and dial pulses can thereafter be generated in a well-known manner.

REFERENCES:
patent: 1548092 (1925-08-01), McClarence
patent: 3325599 (1967-06-01), Clark, Jr.
patent: 3513271 (1970-05-01), Stathacopoulos
patent: 3536851 (1970-10-01), Burns
patent: 3761639 (1973-09-01), Uno

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