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| Number | Title | Issue Date |
| 7206403 | Telephone terminal equipment interface circuit The object of the present invention is to remove the dead region of a diode bridge and maintain stable operations in a telephone terminal equipment interface circuit. In order to realize this object, a telephone terminal equipment interface circuit, according to the... | 04/17/2007 |
| 7103175 | Systems and methods for an electronic hook switch for customer premises equipment Embodiments of the present invention relate to systems and methods for an electronic hook switch for customer premises equipment. In an embodiment, a system includes a first lead configured to be coupled to a tip wire and a second lead configured to be coupled to a ... | 09/05/2006 |
| 7094110 | Computer disconnect device A computer disconnect device that may have an external communications cable connector; a jumper communications cable connector; a switch; external wiring for connecting the external communications cable connector to the external side of the switch; and jumper wiring... | 08/22/2006 |
| 6925170 | Wire-bound telecommunication device and a circuit for use in such a device In known telephone subscriber end stations a caller_ID IC detects a tone alerting signal TAS alerting that successive caller_ID information can be received for displaying on a display of the phone. The known station applies narrow frequency band filters to detect to... | 08/02/2005 |
| 6868156 | Non-voice signal repeater for speech coders A method of repeating a non-voice signal such as a dual tone, multiple frequency (DTMF) signal, by inserting a delay sequence of data values into an output data sequence of data values, a portion of the output data sequence following the delay sequence being the sam... | 03/15/2005 |
| 6845157 | Linear polarity guard and method for DSL-ready pots devices A plain old telephone system (POTS) device, for example but not limited to, a telephone, facsimile machine, analog modem, caller identification (ID) system, speaker phone, cordless phone, etc., employs an on-board transistor-based linear polarity guard to enable dec... | 01/18/2005 |
| 6832721 | Authentication system using information on position An authentication system and method uses information on a position of a card as determined, for example, by detecting a position of a user's cell phone and the position of a card reader determined from card reader identification data. If the card is used in a card r... | 12/21/2004 |
| 6829352 | Amplifier arrangement Amplifier arrangement comprising: a resistive receive hybrid means adapted to pass a combination of a received signal and a transmitted signal, a resistive transmit hybrid means adapted to pass substantially only t... | 12/07/2004 |
| 6631190 | Telephone system A telephone system capable of judging kinds of various signals (line input signals) obtained through a line is disclosed, that enables reduction of the number of parts, detection with high accuracy, reduction of a mounting area, and reduction in costs. Th... | 10/07/2003 |
| 6393123 | Method and modem circuit for determining connection status of a phone line A circuit for determining connection status of a phone line shared by multiple telecommunications devices, such as modems and phones, is provided. The phone line includes respective tip and ring lines. The circuit comprises a first transistor stage couple... | 05/21/2002 |
| 6141416 | Analog telephone subscriber terminal apparatus An analog telephone subscriber terminal apparatus with means for realizing additional functions is provided. In the on-hook state of the subscriber terminal apparatus, and outside of the idle operating state of the subscriber terminal apparatus, a current... | 10/31/2000 |
| 6044150 | Method and apparatus for a host-based personal computer speakerphone A method and apparatus for implementing a speakerphone within a personal computer having a voice-capable modem and an audio board is provided. The personal computer executes host software providing the user interface for speakerphone operation and the ind... | 03/28/2000 |
| 5812658 | Method and circuit for failsafe switch-hook detection during fault in a telephone system A circuit and method for maintaining switch-hook detection (SHD) in the presence of a fault in a telephone system may include a comparison of one of a tip current and a ring current to a reference current. A switch-hook detection indicates that a request ... | 09/22/1998 |
| 5659602 | Telephone apparatus for caller ID A telephone apparatus for connection to central office equipment to receive a caller ID signal therefrom and having an operating mode in which line current is less than a threshold at which off-hook state is detected, the line current drawn in said mode b... | 08/19/1997 |
| 5600715 | Integrated loop current detector apparatus for a PSTN modem An integrated loop current detector for a public switched telephone network modem. The present invention solves the loop current detect problem in general, and is especially useful in modems employing echo cancellation techniques due the linearity afforde... | 02/04/1997 |
| 5559873 | Telephone privacy device with conference and indicator features A simple and inexpensive telephone exclusion or privacy device. A conference feature is and am indicator light showing when the line is in use are also provided. The basic exclusion or privacy circuit includes only eleven components, thereby providing a v... | 09/24/1996 |
| 5461670 | Telephone subscriber system incorporating a drive interface for a telephone line switch at a different reference potential A telephone subscriber system comprising a speech circuit and a ring circuit adapted to be integrated monolithically to a semiconductor material substrate and being coupled to a telephone subscriber line, respectively through first and second circuit swit... | 10/24/1995 |
| 5287404 | Telephone subscriber line voltage change detection Changes in a telephone subscriber line voltage are detected in a telephone set by supplying a voltage dependent upon the subscriber line voltage to a potential divider having first, second, and third tapping points, the second tapping point being between ... | 02/15/1994 |
| 5255182 | Payment card point-of-sale service quality monitoring system, apparatus, and method A system for determining the cause of lost, delayed or erroneous responses in a network for authorizing payment card transactions from the point of view of the point-of-sale terminal that forms part of the network. A request for authorization is entered i... | 10/19/1993 |
| 5155764 | Telephone set with on-hook line seizure A telephone set is provided enabling seizure for originating and terminating calls of a telephone line connected thereto to be performed as well as release thereof, as the result both of a first command produced by a first switching entity actuated from t... | 10/13/1992 |
| 5111502 | Telephone line bridging sensor A telephone line bridging sensor circuit is provided which provides a variable output frequency signal to a microprocessor for measuring and storing the frequency count on a periodic basis. The circuit includes an isolation transformer to isolate the audi... | 05/05/1992 |
| 5020100 | Telephone line loop current regulator A telephone line loop current regulator combines the functions of current regulation, current detection, loop disconnect signalling and speech switching. It comprises a gyrator circuit formed by resistor (R1), capacitor (C1), transistor (T1) and resistor ... | 05/28/1991 |
| 4935959 | Two-wire telecommunications line detection arrangements A loop closure detector for a two-wire telephone line comprises a four-arm resistive bridge, in which the four arms are constituted respectively by a first battery feed resistor, the two-wire line in series with a second battery feed resistor, and two res... | 06/19/1990 |
| 4899379 | Circuit arrangement for the connection of line circuits of a digital time multiplex-telephone network A circuit for implementing a connection of an operational amplifier, and for achieving the switchable sensitivity of the same, as well as the in-and-out switchable filter elements, which results in a low cost, universally applicable line circuit interconn... | 02/06/1990 |
| 4864605 | Telephone trunk interface circuit A solid-state telephone trunk interface circuit provides high isolation between a central office and telephone equipment. Opto-isolator transistors and a transformer are used to isolate the central office and the local equipment portions of the circuit. A... | 09/05/1989 |
| 4841568 | Circuit arrangement for a telephone station with earth connection to the central supply device A circuit arrangement for a telephone station with earth connection to the central supply device for the purpose of post-dialing signaling, operates independently of whether the negative or the positive pole of the exchange battery is earthed. This is ach... | 06/20/1989 |
| 4809322 | Circuit arrangement for a telephone station with ground connection The invention relates to a circuit arrangement for a telephone station with ground connection to a central supply device for the purpose of post-dialling signalling. The circuit arrangement operates independently of which terminal of an exchange battery i... | 02/28/1989 |
| 4454477 | Loop current detector with threshold setting impedance In a loop circuit closure detector, a circuit which connects a voltage comparator to the loop circuit is biased so that the comparator indicates loop circuit closure at a predetermined minimum non-zero value of loop current. Comparator inputs are both cou... | 06/12/1984 |
| 4444999 | Automatic electronic disconnector for subscriber terminal equipment An electronic circuit means for automatically disconnecting an off-hook subscriber's first telephonic signal sending and receiving terminal device which is in an off-hook mode when a second terminal device is taken off-hook. The disconnector circuit means... | 04/24/1984 |
| 4439634 | Carrier subscriber telephone off-hook detector A resistor and diode means are electrically connected in series between nodes A and B on the base electrodes of first and second transistors of a differential amplifier. These nodes A & B are also connected to a source of temperature-compensated load-sens... | 03/27/1984 |
| 4320265 | Line repeater for telephone system using radio links A telephone exchange communicates with a number of scattered local stations via radio links extending from a central terminal to respective peripheral installations each comprising a radio transceiver coupled via a repeater to the line loop of an associat... | 03/16/1982 |
| 4319092 | Current detection circuit arrangement for an automatic telephone exchange Current detection circuit arrangement for an automatic telephone exchange for detecting currents in a system of two conductors having earth as the common return conductor. This circuit arrangement comprises a pair of measuring resistors R1, R' | 03/09/1982 |
| 4224478 | Data transmission circuit for establishing a bidirectional data path in a telephone system A data transmission circuit for use in a telephone system. The telephone system includes a telephone line connected with tip and ring terminals and a subscriber telephone coupled across the tip and ring terminals. The on/hook condition of the telephone is... | 09/23/1980 |
| 4220825 | Telephone status monitor circit A telephone status monitor circuit for determining the on/hook and off/hook conditions of a telephone connected across standard tip and ring terminals of a telephone system. The telephone status monitor circuit includes a charging circuit, in the form of ... | 09/02/1980 |
| 4216355 | Telephone line monitoring apparatus An apparatus is disclosed for monitoring the busy or free condition of telephone subscribers' lines, comprising a number of bridge circuits, each connected to one of the subscribers' lines. Each bridge circuit includes a discriminator which generates a si... | 08/05/1980 |
| 4172215 | Transformer coupling circuit providing for cancellation of D.C. fluxes In a coupling circuit for A.C. coupling a switching network to a trunk circuit through a coupling transformer, a magnetic flux cancel circuit is provided for canceling non-varying magnetic fluxes produced by direct current components of a switch-hold curr... | 10/23/1979 |
| 4151377 | High impedance loop-seizing and dial pulsing circuit An improved loop-seizing and dial pulsing circuit arrangement of the type employed in telephone trunks has an extremely low insertion loss. The circuit comprises a diode bridge connected across a telephone loop and a controlled constant current source con... | 04/24/1979 |
| 4126765 | Detector circuit for sensing battery polarity and loop closure A detector circuit for use in conjunction with a trunk circuit of a PABX telephone system interfacing with a central office providing for constant monitoring of normal or reverse battery application by the central office during the high impedance idle sta... | 11/21/1978 |
| 4105872 | Electronic telephone system including interexchange trunk repeaters for traffic with other systems An electronic telephone switching system is described having peripheral units including a plurality of subscriber and line circuits, a plurality of trunk and tie line circuits, at least one attendant line circuit, a plurality of signaling tone receivers, ... | 08/08/1978 |
| 4099032 | Loop current detector A ground start loop current detector is used to monitor the loop current in a telephone subscriber loop when the subscriber requests service by grounding one line of the loop (ground start), when a busy subscriber discontinues use by opening the loop, and... | 07/04/1978 |
