Keptel, Inc.

Antec, Incorporated

Steven B Perry

Daniel Lynch

James P Hogan

Thomas J Collins

Joseph Miller

Methods and apparatus for using and/or switching to an auxiliary communication pathway to increase system reliability and/or reduce maintenance costs is disclosed. One feature is directed to a smart network interface device (SNID) implemented using latching relays. The SNID has very low power requirements and can be remotely controlled in a reliable manner through the use of simple tone signal commands over common POTS line pairs. Upon detecting a fault condition on a main line pair, the SNID is remotely instructed to disconnect the faulty line pair and switch the telephone customer's line connected to the faulty line pair to an auxiliary line pair. To operate in a POTS telephone environment without the need for an additional power supply, the SNID is designed to be powered from the power available from the auxiliary line pair. The power supply circuitry of the SNID is designed to have a near infinite input impedance with regard to input signals below twenty volts. Tone signals which are readily generated by equipment commonly found within the telephone network are used as control signals to reduce the cost associated with providing a command transmitter. Control signals of relatively long durations, e.g., in excess of 0.1 second, are used to reduce the accuracy required of the tone generation and detection equipment needed and to reduce the chance of erroneous command signals.

Methods and apparatus for providing an auxiliary communication line

A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver.

Channel interface unit

A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver The channel interface unit also includes a device for decreasing effective capacitance by modifying the output impedance of the driver.

A timing circuit and apparatus that utilizes this circuit. The apparatus is particularly suited for use with a telephone network interface, for substantially preventing a third party who gains access to the interface from placing an unauthorized telephone call through a network connection obtained through a jack, typically modular, located in a customer portion of the interface. Specifically, this apparatus is connected in series within the telephone company side of the interface to illustratively a ring lead of an incoming subscriber loop. In operation, the apparatus provides network access, by supplying loop current, on a timed periodic (repetitive) basis to a telephone (or other equipment through which a telephone call can be placed) plugged into the jack located within the network interface. Access is provided for a period of time that is sufficient to test loop current but is insufficient to allow the network to complete a call dialed from that telephone over this loop. However, between any two successive intervals during which the apparatus supplies loop current to the telephone, the apparatus interrupts this current for a period of time that is sufficient for a switching machine at a local central office that serves this loop to interpret the cessation of current as an on-hook condition, completely terminate any call that may be in progress for this telephone and reset the loop.

Timing circuit and a secure telephone jack utilizing this circuit

Apparatus for disconnecting and reconnecting equipment to a telephone line in response to a signal sent over the telephone line. The apparatus includes a voltage threshold circuit, a voltage regulator circuit and a switching and timing circuit. The switching and timing circuit includes a first energy storage capacitor and a first discharge circuit. The switching and timing circuit further includes a second energy storage capacitor and a second discharge circuit and further includes a third energy storage capacitor and timing resistor. The first discharge circuit includes a first semiconductor switching device and a relay coil of a latching relay. The second discharge circuit includes a second semiconductor switching device and a second relay coil of the latching relay. When a signal is sent over the telephone line which exceeds the threshold level, it is regulated by the voltage regulator and charges up the first, second and third storage capacitors in an order such that the third capacitor charges first, the second capacitor next and the first capacitor last. Once the signal disappears from the telephone line, the first storage capacitor discharges into the first discharge circuit, thereby placing the switch into a first switching state and disconnecting the customer equipment. In this state, a test circuit, for example, may be connected to the telephone line to enable the central office to test the telephone line for faults. After a predetermined time delay determined by the discharge of the third energy storage capacitor into the timing resistor, the second discharge circuit is activated by a voltage differential between the second and third storage capacitors whereby the switch is switched from the first state back to the second state, thereby reconnecting the customer equipment, for example, a telephone, back to the telephone line.

Remotely activated switching apparatus

Various embodiments of a ground start circuit suited for use in telecommunication applications, illustratively in conjunction with a ground start line, and a method for use in the circuit for invoking ground start operation on such a line are described. In essence, as soon as a telephone line is connected across the inventive ground start circuit, a potential difference that appears between a ring side of a two-wire telephone line and earth ground causes a control voltage internal to the circuit to increase in magnitude. Once this control voltage reaches a threshold value, then the circuit establishes a low impedance path between the ring side of the line and earth ground in order to place the line in an unbalanced condition. This low impedance path is maintained until a central office connected to the line at a remote end thereof senses the unbalanced condition and, in response, applies battery voltage to the line to cause loop current to flow therethrough, i.e. through a loop formed of tip and ring wires that form the line. As soon as the inventive circuit detects the presence of loop current through, for example, a resistive loop current detector, the circuit eliminates the low impedance path thereby returning the telephone line to a balanced condition. At this point, the inventive circuit becomes substantially electrically transparent to normal functioning of the line. The central office then applies dial tone to the line in order to allow a caller to initiate an outgoing call.

Ground start circuit

An apparatus and method for decoding ringing signals on a party telephone line coupled to the telephone line and a telephone instrument, according to the polarity of a d.c. voltage level present across the telephone line upon which ringing signals are superimposed and according to the grounded state of the telephone line. The apparatus comprises a discrimination circuit which supplies a selected one of the ringing signals to the telephone instrument via a ringing signal path to actuate the ringer of the telephone instrument. The apparatus further comprises a ringing signal rectification circuit connected to the telephone instrument via a voice signal path for preventing the ringing signal present on the telephone line from activating a ringer of the telephone instrument via the voice signal path. A switching circuit selectively connects the telephone instrument to the ringing signal path and the voice signal path. The apparatus further preferably comprises a circuit for eliminating bell taps and a balancing circuit for balancing the impedance across telephone line when the d.c. voltage level on the telephone line falls below a preset threshold, thereby forcing semiconductor devices on the line which could contribute to noise problems when only in a partly conductive state, into a conductive state, thereby eliminating the noise.

Programmable selective ringing circuit and method for party telephone

An apparatus adapted to be coupled into a party telephone line for selecting a ringing signal transmitted on the line from among a plurality of possible coded ringing signals that could be transmitted on the line and for coupling the ringing signal to a telephone is disclosed. The apparatus comprises a rectifier coupled to the party line for providing a rectified ringing signal, a first switch having the rectified signal as an input for reversing the polarity of the rectified signal at selected times, a second switch coupled to the first switch for selecting either the rectified ringing signal or the ringing signal itself and a third switch coupled to the second switch for coupling the selected signal to a telephone coupled to the third switch. A control unit comprising a microprocessor is provided which evaluates the incoming ringing signal to determine its frequency and controls the first, second and third switches to route the ringing signal to the telephone if it is of the proper frequency after any necessary frequency conversion which is performed under control of the microprocessor. Frequency conversion is performed by appropriate control of the first switch coupled to the output of the rectifier.

Frequency responsive party telephone line selection apparatus and method

A circuit for connection into a telephone line for detecting when a telephone instrument has gone off-hook and which is unaffected by the presence of a ringing signal on the telephone line. The circuit comprises a transistor switch, a first plurality of series connected diodes connected in series with the telephone line for developing a first voltage thereacross when the telephone instrument has gone off-hook, an RC circuit coupled to the first plurality of diodes for charging to the first voltage when the telephone instrument has gone off-hook after a time delay and for activating the switch, a second plurality of series connected diodes, the second plurality being greater than the first plurality, the second plurality of diodes being connected to the switch and to the first plurality of diodes for developing a second voltage thereacross during one half cycle of a ringing signal on the telephone line. The first plurality of diodes develops the first voltage during a second half cycle of the ringing signal on the telephone line. The first and second voltages are of opposite polarity, such that the charging circuit alternately charges toward the first and second voltages during a ringing signal. The charging circuit has a time constant such that it never charges to a voltage during a half cycle of the ringing signal sufficient to activate the switch and on the average, the charging circuit maintains the control input of the switch substantially intermediate the first and second voltages.

Telephone off-hook detector circuit

A telephone line testing circuit for determining whether a fault exists on a telephone line entering a customer's premises or whether the fault exits in the customer's wiring and equipment. The testing circuit comprises a test switch, a polarity detector, a current detector, a dial tone detector and an indicator. The polarity, current and dial tone of an incoming telephone line signal are tested sequentially in the same circuit and in one operation such that if any one of the three characteristics of the entering telephone line contains a fault, the indicator will not generate a signal. When the entering telephone line signal has the correct operating polarity, sufficient operating current draw and a dial tone of the correct operating frequency, the indicator will generate a signal indicating that no fault exits on the entering telephone line.

Telephone line testing circuit

Network interface enclosure

Apparatus is disclosed for disconnecting and reconnecting equipment to a telephone line in response to at least one signal sent over the telephone line. The apparatus includes a voltage threshold circuit, a voltage regulator circuit, a current chargeable element such as a capacitor, a discharge circuit, a switch and a switch control. The switch is coupled to the telephone line and to the equipment and disconnects the equipment from the line in response to the signal sent over the line. The threshold circuit is coupled to the line and receives the signal. It provides an output signal to the regulator circuit only when the signal on the line exceeds a threshold voltage level. The voltage regulator circuit regulates the voltage at the output of the threshold circuit and provides a substantially constant voltage to the chargeable element. Since the voltage applied to the chargeable element is known, the time required to charge the chargeable element can be precisely determined. The chargeable element is coupled to the discharge circuit which causes the chargeable element to discharge when the signal to the threshold circuit falls below the threshold value, for example, when the signal is removed. The switch control is coupled to the discharge circuit and maintains the switch in a switched, equipment-disconnected condition while the chargeable element is discharging.

Remotely-activated switching apparatus

Apparatus is disclosed for disconnecting and reconnecting equipment to a telephone line in response to at least one AC signal sent over the telephone line. The equipment can automatically be reconnected after a predetermined time period, or reconnected only after another AC signal is received. The apparatus includes digital circuits for detecting a signal within a predetermined frequency range which is present uninterrupted for a minimum time period to activate switching. The apparatus also includes digital timing circuits which can provide relatively long time periods during which the equipment is disconnected which do not utilize large energy storage devices. The digital circuits of the apparatus are operable at extremely low currents, e.g. less than 30 ua total drain. The regulator utilizes one or more light-emitting diodes drawing a current of only about 5 ua to generate a reference voltage.

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Highlands, NJ, United States of America

Steven B Perry