METHOD AND APPARATUS FOR
PREVENTING PAY TELEPHONE FRAUD
AND REDUCING HANDSET VANDALISM
 Inventor: Patrick J. McGarry, West Chester, Pa.
 Assignee: Mars Incorporated, McLean, Va.
 Appl. No.: 407,899
 Filed: Sep. 15, 1989
 Int. CI.' H04M 17/02
 U.S. CI 379/145; 379/146;
 Field of Search 379/146, 145, 147, 155
 References Cited
U.S. PATENT DOCUMENTS
3,676,597 7/1972 Peterson .
4,039,768 8/1977 O'Maley .
4,845,742 7/1989 Staggs et al 379/155
4,862,494 8/1989 Matheny '. 379/145
Primary Examiner—Stafford D. Schreyer
Attorney, Agent, or Firm—Davis Hoxie Faithfull &
A method and apparatus for the detection and prevention of pin fraud in a coin operated telephone is disclosed. A circuit detects loss of loop current and triggers the opening of a pair of switches thereby disconnecting the microphone from the phone. The A-relay is also switched to its refund and collect position. As a result, the fraud path through the microphone is disconnected, and the central office can perform all its control functions unimpaired. Thus, the incentives for perpetrating the fraud are eliminated.
18 Claims, 4 Drawing Sheets