US Patent No: 4,726,057

Number of patents in Portfolio can not be more than 2000

Answer detection method and apparatus for coin telephone sets

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ATTORNEY / AGENT: (SPONSORED)

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Abstract

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A coin operated telephone station is provided with apparatus for detectinghen a called party has answered a call (initiated at the coin operated telephone station) by the measurement of incoming signal energy on the telephone line. The apparatus includes hardware and software that cooperate in providing efficient and reliable detection of called party answer for the purpose of accurately charging telephone users. A microprocessor samples the output from each of three specialized energy detectors every 20 milliseconds to determine whether called party answer has occurred. The energy detectors include: (1) call progress tones in the frequency band 200-700 Hz approximately; (2) special information tones; and (3) broadband energy in the frequency band above 200 Hz. Additionlly, the time duration of the call progress tones and the quiet intervals between them are measured and used in the answer detection process. Signal energy from the calling party in the 200-700 Hz frequency band is filtered from the transmitting path by a 1200 Hz high-pass filter until called party answer occurs. Such filtering precludes a user from interfering with the detection process while permitting a limited amount of information to be tranmitted in the event that the answer detector is slow to operate.

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Patent Owner(s)

Patent OwnerAddressTotal Patents
AMERICAN TELEPHONE AND TELEGRAPH COMPANYMURRAY HILL, NJ3147
AT&T INFORMATION SYSTEMS INC.MURRAY HILL, NJ371

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Doerry, Armin W Albuquerque, NM 20 62
Noonan, Dennis J Indianapolis, IN 1 20

Cited Art Landscape

Patent Info (Count) # Cites Year
 
Bell Telephone Laboratories, Incorporated (1)
4,384,175 Tone detection method and arrangement for observing and classifying repetitive status signals 5 1981
 
Feller AG (1)
4,296,277 Electronic voice detector 16 1979
 
INTERNATIONAL BUSINESS MACHINES CORPORATION (1)
4,563,681 Tone receiver for digital data communication systems 9 1983
 
NORTEL NETWORKS LIMITED (1)
4,277,650 Single frequency tone receiver 6 1979
 
TRANSWAVE, A PARTNERSHIP (1)
4,484,035 Dual tone multi frequency digital detector 11 1983

Patent Citation Ranking

Forward Cite Landscape

Patent Info (Count) # Cites Year
 
SECURUS TECHNOLOGIES, INC. (15)
5,319,702 Method and apparatus for detecting and responding to hook flash events occurring on a remote telephone 64 1992
5,805,685 Three way call detection by counting signal characteristics 57 1995
5,796,811 Three way call detection 39 1996
6,665,376 Selectively activated integrated real-time recording of telephone conversations with automated documentation of consent to call recording 40 1998
6,611,583 Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access 34 1998
6,665,380 Inmate messaging system and method 33 1999
6,763,099 Advanced three way call detection system and method using spread spectrum techniques 19 1999
6,668,045 Message screening, delivery and billing system 33 2000
6,920,209 Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access 25 2002
7,248,680 Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access 5 2003
7,899,167 Centralized call processing 6 2003
8,000,269 Call processing with voice over internet protocol transmission 2 2004
7,916,845 Unauthorized call activity detection and prevention systems and methods for a Voice over Internet Protocol environment 0 2006
7,529,357 Inmate management and call processing systems and methods 18 2007
8,340,260 Inmate management and call processing systems and methods 0 2009
 
AT&T Bell Laboratories (1)
5,222,122 Payphone having master and slave modes 15 1992
 
SCIENCE DYNAMICS CORPORATION (1)
7,505,406 Public telephone control with voice over internet protocol transmission 11 2001
 
SECURUS TECHNOLOGIES HOLDINGS, INC. (1)
7,889,847 Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access 14 2006
 
SUBSCRIBER SOLUTION, INC. (1)
6,560,323 Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access 35 1997
 
SUBSCRIBER SOLUTIONS (1)
7,106,843 Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access 117 1998