Abstract: A subscriber-line interface circuit (SLIC) has tip and ring amplifiers connected to the tip and ring lines, respectively, of customer premises equipment (CPE). The SLIC returns the ringing signal (provided to the CPE from a power supply connected to the CPE's ring line), to ground or to battery, through the SLIC's tip amplifier. In one embodiment, the SLIC has three switches: S1 connecting the power supply to the ring line, S2 connecting the ring amp to the ring line, and S3 connecting the tip amp to the tip line. During ringing, S1 and S3 are closed to return the ringing signal to ground through the tip amp, which is preferably driven to saturation during ringing to reduce power consumption. By eliminating the fourth switch that appears in prior-art SLICs (e.g., connecting the tip line to ground), SLICs of the present invention can be smaller and therefore less expensive to implement.

Abstract: A communication system of the present invention utilizes ring detection circuitry on both sides of an isolation barrier. More particularly, the ring detection circuitry may include ring burst circuitry on the phone line side of the isolation barrier and ringer timing circuits on the powered side of the isolation barrier. The digital burst peak signal may be transmitted through the isolation banier to the finger timing circuits. By splitting the ring detection circuitry so that the ringer timing circuits are placed on the powered side of the isolation barriers, a significant reduction in the power usage on the phone line side of the barrier related to the ring detection function may occur. The outputs of the ringing timing circuits may be provided to circuits on either side of the isolation barrier. Thus, the ring detection function may be accomplished in a system utilizing an efficient bidirectional capacitive barrier while still minimizing power usage on the line side of the barrier.

Abstract: A power management circuit for a remote access platform extracts power from a wireline for powering a ring generator that generates a ringing voltage signal that is distributed to a plurality of subscriber circuits. A power-limited voltage converter steps up the wireline voltage to a higher ‘isolating’ voltage, charging a capacitor coupled to the ring generator. A monitor circuit reduces the power that the power-limited voltage converter can draw, if the wireline voltage drops too low. This prevents the wireline voltage from collapsing should the remote terminal be deployed at a distance from wireline voltage source (the central office) greater than its specified capability.

Abstract: A power switch device is used with a telephony instrument that is connected to a local phone loop via two telephone wires and that has two power lines for connection to a power source. The device includes a rectifier connected to the telephone wires, and a latching relay having an exciting coil connected to the rectifier via a differentiator, and a switch unit. The coil is excited by current flowing through the differentiator when a ring signal is present at the telephone wires so as to enable the switch unit to make connection between the power lines and the power source. An integrator is connected between the rectifier and the coil, and discharges when neither the ring signal nor a talking signal is present at the telephone wires so as to excite the coil and enable the switch unit to break connection between the power lines and the power source.

Abstract: An apparatus and method for enabling Cisco legacy power to support IEEE 802.3 AF standard power. A network power system capable of delivering data terminal equipment power via a media dependent interface includes power source equipment according to Cisco legacy power and at least one powered device according to IEEE standard power. A power compatibility module is inserted between the power source equipment and the powered device to enable the power source equipment to appear according to IEEE standard power and the powered device to appear according to Cisco legacy power. The module includes switches, a DC/DC converter, an IEEE power source equipment circuit, and an isolator. The module optionally includes a user signaling device for communicating operating conditions of the module to a user. The module may be connected to two ports of the power source equipment to supply adequate power levels to the powered device.

Abstract: The invention relates to an SLIC circuit (1), which is connected directly to a telephone line (2), for joint transmission of voice and data via the telephone line (2), with adequate echo attenuation achieved even at high data frequencies in that a first current which corresponds to the sum of the transmission and received currents (Ia, Ib), and a second current (Id) which corresponds to the current produced by the transmission power level (Vtx) at the data frequency, are produced, and the difference between the first current and the second current (Id) is emitted.

Abstract: A subscriber's telephone system is presented that includes at least one driver circuit connected to Tip and Ring terminals. An additional network is connected between an output of the driver circuit and the Ring terminal. This additional network includes a suitably dimensioned capacitor and a diode limiter connected in parallel with each other to minimize the overall voltage while maintaining a desired battery mean value.

Abstract: A telephone comprises an acoustic alarm, conversation members, first control means for the acoustic alarm, second control means for the conversation members, first supply means and second supply means for absorbing energy from a telephone line, the first supply means and the second supply means supplying the first control means in a call condition and the second control means in a conversation condition, respectively, wherein the first supply means further supplying the second control means in the call condition.

Abstract: A terminating device for interconnecting service provider wiring with subscriber wiring includes a base, a customer bridge, a removable cover and insulation displacement contacts for terminating the service provider wiring and the subscriber wiring. The insulation displacement contacts for the subscriber wiring are housed within the customer bridge and terminate the subscriber wiring by moving an actuating arm from a disconnected position to a connected position. The insulation displacement contacts for the service provider wiring terminate the service provider wiring by moving a stuffer from a disconnected position to a connected position. The cover includes a locking slide having a movable clasp for deterring unauthorized access to the customer bridge, while permitting authorized access. A plug on the cover and a jack on the base each have a resilient seal that telescope together to effectively seal test contacts located within the jack when the plug is inserted into the jack.

Abstract: A digital subscriber line and POTS voice interface between a telephone line and central office equipment is provided. For POTS band frequencies, a reactive impedance coupled across the two wire interface of the POTS line card, and serially coupled to the line side of the DSL coupling transformer, has an open state magnitude. The magnitude of the line side windings of the DSL coupling transformer is low at POTS band frequencies. POTS band signal power is therefore delivered to the POTS line card. For DSL band frequencies, the reactive impedance across the POTS line card has a closed state magnitude. The POTS line card is therefore essentially short-circuited at DSL band frequencies, and DSL band signal power is delivered to the DSL modem. The frequency band in which the reactive impedance transitions from an open state magnitude to a closed state magnitude corresponds to the frequency band between the POTS frequency band and the DSL frequency band.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end to provide a communication path for signals to and from the phone lines. Briefly described, a means for providing a proper hookswitch transition for a variety of international phone standards is provided. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DAA circuitry may be utilized which satisfies many or all hookswitch transition standards without the use of additional discrete devices. The hookswitch transition standards may be satisfied by ramping down the current flowing through the hookswitch prior to transitioning the hookswitch state. In this manner the hookswitch current change as a function of time (di/dt) may be decreased. Thus, the current through the hookswitch may be actively controlled prior to switching the hookswitch from an off-hook condition to an on-hook condition.

Abstract: A line card or other telephone or communications interface provided with a ringing SLIC outputs relatively high voltage, such as in excess of about 90 volts, and/or relatively high current such as in excess of about 20 milliamps during normal use, but decreases the voltage or current of a ringing signal or other signal upon occurrence of a tip and/or ring line fault or other abnormal condition. The abnormal condition is detected by measuring voltage and/or current on the tip line and/or ring line. In response to an excess voltage or current, the ringing current or other output current is reduced to achieve desired safety and/or compliance with standards.

Abstract: A redundant ringing signal generator subdivides a ringing signal bus into multiple ringing bus segments. A plurality of redundant ringing voltage generators sourcing internally and/or externally ringing voltages are individually and selectively connectable to the multiple ringing bus segments. In the event of a prescribed anomaly in the ringing signal sourced by a ringing generator, the faulty ringing signal is automatically disconnected from its associated ringing bus segment, and that ringing bus segment is connected to a redundant ringing signal source, provided by either the same or another ringing generator.

Abstract: A telecommunications device including a plurality of splitter cards mounted in a chassis, a circuit board, and plurality of card edge connectors for providing electrical connections between the splitter cards and the circuit board, and POTS, LINE, and DATA connectors. The circuit board includes three layers, each layer having tracings that electrically connect at least one POTS, LINE, or DATA connector to at least one of the card edge connector. A center layer includes a grounding plane that is adapted to reduce cross-talk between tracings on a top layer and tracings on a bottom layer. The grounding plane is co-planar with tracings on the center layer such that the grounding plane adds additional thickness to the center layer.

Abstract: A telecommunications device including a chassis having a card housing for containing a plurality of splitter cards. The card housing includes front and back ends. The front end of the card housing defines an access opening for allowing the splitter cards to be inserted into or removed from the card housing. The device also includes a plurality of card edge connectors for providing electrical connections with the splitter cards. The card edge connectors are located within the card housing adjacent to the back end of the housing. Each card edge connector is arranged in a generally horizontal orientation. The device further includes forwardly facing LINE, POTS and DATA connectors that are electrically connected to the card edge connectors. At least the LINE and POTS connectors are positioned in a generally horizontal orientation.

Abstract: A network interface device includes an enclosure that houses active electronics for accommodating twisted-pair telephone wires and coaxial cable. The housing has a base that connects to a building wall. A shield locates within the housing, the shield having a platform and a perimeter wall that extends around the platform. A printed circuit board mounts within the shield between the base and the platform. The shield is hinged to the base so that it may be readily removed with the printed circuit board if repair is needed. A subscriber bridge module mounts on the platform. The subscriber bridge module has subscriber line termination points on one side that electrically connect with the subscriber lines. The subscriber bridge module also has telephone jacks electrically connected between the subscriber termination points and the provider line. This provides a demarcation between the subscriber lines and the provider line.

Abstract: The present invention provides an improved method of protecting a subscriber telephone interface circuit from the application of excess voltages and currents. The method uses a standard subscriber telephone interface circuit, including a speech circuit and a ringing detection circuit, in conjunction with updated controlling software. When excess voltage or current is detected by the ringing detection circuit, a CPU disconnects the speech circuit. The speech circuit is reconnected when the excess voltage or current is removed. The present invention further provides a ringing detection circuit that connects a speech circuit when a ringing signal is detected, and disconnects the speech circuit when excess voltage or current is detected.

Abstract: A ‘lifeline’ POTS back-up mechanism is operative to provide emergency plain old telephone service connectivity over a span-powered two-wire metallic digital subscriber loop pair, in response to a customer's phone going off-hook, during a lack of normal operating condition of the digital circuit path. A ground fault interruption signal is generated in a remote terminal and used to activate respective POTS by-pass paths in the remote terminal and a central office terminal.

Abstract: A communication system and method for allocating overhead voltage between a telephonic switch and a user device is described. A line driver is located in the telephonic switch and is coupled to the user device. The line driver is in one of a plurality of communication states. A processor, coupled to the line driver, allocates the overhead voltage in response to the communication state of the line driver.

Abstract: The invention relates to device for connecting a subscriber line SUB to a high frequency link HF and to a low frequency link BF, the device comprising a transformer TR disposed between said subscriber line SUB and a signaling link SL, the transformer TR comprising a coupling coil CC designed to be fed by an encoder CODEC, the device also comprising a first switch SW1 for injecting either a ringing signal RS or a power supply signal DC into said signaling link SL in response respectively to a first state and a second state of a control signal CS. In addition the device comprises a second switch SW1 for connecting or disconnecting the feed of said coupling coil CC in response respectively to the second and to the first states of said control signal CS.

Abstract: An apparatus and method for providing a ringing voltage to a communication device such as a telephone or a modem. Typically, communication devices are coupled to a ringing voltage providing telephone network, such as a Plain Old Telephone Service (POTS) network. The POTS network generally provides the necessary ringing voltages to the communication device. However, in other telephone networks, such as a PBX system, ringing voltages are not provided by the telephone network. The apparatus provides ringing voltages to the communication devices coupled to the non-ringing voltage providing telephone networks. The apparatus includes a switching regulator that provides the necessary ringing voltages to an indicator such as a bell or other output indicator.

Abstract: A ringing voltage power management circuit is configured to extract an isolated high-value intermediate voltage from a central office powered digital subscriber line through a current limiting circuit, and to charge a storage capacitor that serves as an energy reservoir for the ring generator of a subscriber line circuit. The storage capacitor and the current limiting circuit isolate the peak power drawn by the ringing load from the telephone line and translate the ringing signal's (20 Hz) ripple to the sub-Hz oscillations of the ringing cadence.

Abstract: A line powered codec which adaptively allows operation with power supplied from a telephone line in many countries as conditions warrant. A startup procedure uses country-specific register settings, which are powered and maintained from a low voltage side other than the telephone line. Thus, during low line power conditions a programmed state of the line powered codec can be maintained even after a power loss in the telephone line. In another aspect, a current and voltage detection module in the line powered codec is always powered from the telephone line. If sufficient power is not present, the line powered codec does not power up. In yet another aspect, a plurality of power rails may be provided.

Abstract: Terminals are connected via cables in a star-shaped fashion with respect to a HUB in a LAN. Each of the cables includes therein signal lines and power feed lines. The HUB includes therein a power feed section. The power feed section and the power feed lines of each cable are connected to measure a value of current which flows in the power feed lines. If it is judged based on the measured current value that the terminal connected to the corresponding cable is a telephone terminal, the power feeding to the corresponding power feed lines is continued. On the other hand, if the terminal is judged to be a terminal other than the telephone terminal, the power feeding is stopped.

Abstract: The invention relates to a monolithically integrated telephone circuit for driving wide-band telephone lines and transmitting digital data at a very high frequency. The telephone circuit is powered from a battery DC supply providing a pair of voltage references. The telephone circuit includes an output circuit portion including a pair of differential output stages, each having a pair of inputs and being connected with its output to a respective lead of a two-wire telephone line. The telephone circuit also includes a device for deriving a reference voltage from the supply voltage, and includes a low-voltage supply network which is input a DC signal and produces a voltage reference to be added to the reference voltage for delivery to one input of each output stage. The other input of each stage receives an AC signal in order to present at the circuit output a suitable AC+DC differential voltage for driving the telephone line.

Abstract: A circuit configuration is provided for supplying a telephone subscriber loop with a supply voltage, for transmitting a transmitted signal into the telephone subscriber loop, and for receiving a received signal from the telephone subscriber loop. The telephone subscriber loop has a first line and a second line. The circuit configuration has a supply voltage source with a first terminal and a second terminal between which a supply voltage drops; a first circuit connected with the first line and having first and second supply voltage connections; and a second circuit connected with the second line and having third and fourth supply voltage connections. The first supply voltage connection is connected with the first terminal and the fourth supply voltage connection is connected with the second terminal. A network-side terminal of a telephone subscriber loop and a chip set are also provided.

Abstract: A circuit and supplemental power source connection scheme for a telecommunications modem transmission link are described. The supplemental power source is connectable at any point along a telecommunications wire, including the terminals of repeaters and remote terminals. The combiner circuit includes a diode bridge for ensuring the proper connection of externally connected high voltage power to internal circuitry of the power combiner. The combiner also includes a line polarity matching circuit that automatically configures to signally connect internal positive and negative voltage signals to corresponding positive and negative external signal lines on a telecommunications modem transmission link.

Abstract: During maintenance of telephony equipment the high voltage ring signals for POTS lines must be disconnected or disabled so as to remove the shock hazard potential associated with the substantially elevated ringing voltage present at a line card of a central office. This problem is effectively obviated by installing a three-terminal alarm fuse socket in a circuit path for the ringing generator, and wiring the socket's terminals to enable the fuse to operate as a switch. The switch is closed by inserting a (blown or unblown) three-pin alarm fuse. This enables a ringing voltage generated by the ringing voltage generator to be applied to the span and delivered to the ringing circuit of the handset. The switch is opened by removing the fuse. Ringing voltage functionality for and/or connectivity with the ringing voltage circuit is selectively dependent upon whether a fuse is installed in the receptacle, irrespective of the state of the fuse.

Abstract: A method and circuit for distinguishing between a first voltage signal having a high amplitude and a second voltage signal having a low amplitude, the first and second voltage signals comprising respective AC components superimposed on a DC level. The DC level of the first and second voltage signals is blocked and the respective AC components of the first and second signals are attenuated by an attenuation factor which is voltage dependent and substantially frequency independent, so that the respective AC components of the first and second voltage signals after attenuation have similar amplitudes. The respective attenuated AC components of the first and second voltage signals are then processed so as to distinguish between the first and second voltage signals according to their respective frequencies.

Abstract: A circuit provides a modulation signal to an input terminal of a line modulator which places a line current modulated in accordance with the modulation signal on a telephone line. An amplifier of the circuit amplifies an analog input signal to provide the modulation signal at an output terminal. A first resistor and a first capacitor are coupled in series between a first input terminal of the amplifier and the line, and a second resistor and a second capacitor are coupled in series between a second input terminal of the amplifier and the line. First and second precharge amplifiers are used to precharge the first and second capacitors, respectively, to reduce DC setup time.

Abstract: In a method and a device for controlling the magnitude of the generated ring signal in a the Subscriber Line Interface Circuit (SLIC) the voltage of the A and B lines to the subscriber from the SLIC is compared to a reference voltage. The device is arranged to control the magnitude of the generated ring signal voltage in response to the outcome of the comparison. In particular, the device is arranged to control the ring signal voltage so that the ring signal voltage is reduced if the voltage on the A or B line exceeds the reference voltage. Also, the reference voltage is preferably chosen so that there is no risk for saturation of the final stages. The reference voltage is preferably selected to have a value being related to the value of the negative supply voltage.

Abstract: A subscriber circuit is capable of realizing a CLIP service in an old-fashioned switching system. The subscriber circuit has a ringer transmitting circuit, which is connected to line A and line B, and which transmits a ringer signal in accordance with a ringer transmission request signal from a host system; a battery feed circuit, which supplies speech current to line A and line B; and a timer, which detects, in accordance with a change in the level of a ringer transmission request signal from the above-mentioned host system, the end of transmission of a ringer signal transmitted by the ringer transmitting circuit, starts timer operation, and ends this timer operation after a predetermined time has elapsed. The battery feed circuit supplies speech current to line A and line B from the above-mentioned battery feed circuit during the operation period of the timer.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end to provide a communication path for signals to and from the phone lines. Briefly described, a means for providing a proper ringer impedance for a variety of international phone standards while also providing a proper isolation barrier to the phone line is disclosed. More particularly, a DAA circuitry may be utilized which satisfies many or all ringer impedance standards without the use of additional discrete impedance devices. The ringer impedance standards may be satisfied by use of an impedance structure coupled between the TIP and RING lines and actively controlling the current drawn through the hookswitch devices when a ringing event is detected so as to control the impedance seen at the TIP and RING lines during a ringing event. The detection of the ringing event may be performed on the phone line side of an isolation barrier.

Abstract: Ring-detect interface circuit is disclosed for digital DAA circuitry to provide a plurality of selectable signals, including a ring monitor signal, on a ring-detect output pin. The interface circuitry allows the digital DAA circuitry to interface with advanced controllers, such as advanced DSPs, while still being compatible with older controllers that expect only a ring monitor signal on the ring-detect pin. The interface circuitry may include a multiplexer that receives multiple status bits or signals, including the ring monitor signal, and that has its output controlled by a multiple-bit control register. In addition, the ring monitor signal may be communicated as a digital signal across an isolation barrier from phone line side circuitry to powered side circuitry and ultimately made available on the ring-detect output pin. Corresponding methods for improving compatibility of digital DAA circuitry through the ring-detect interface circuit are also disclosed.

Abstract: In the occurrence of a data modem establishing a data communication session over a telephone line, a method is disclosed for detecting the modem and subsequently reducing the telephone line current. Initially, when a new telephone call is begun, the line current is set as normal to a current sufficient to power a standard telephone handset. Subsequently, using modulation detection techniques, it is determined whether a modem data session has been initiated on the particular telephone line. If such a session has begun, the normal current level on the telephone line is unnecessary since data modems are locally powered. To minimize wasted power and reduce thermal problems caused by the modem dissipating the excessive current, a reduced current is set on the telephone line. This reduced current is either a predetermined modem current level or a minimum allowable current for the particular telephone line, as calculated within the line interface circuit.

Abstract: A telephone line current amplifier comprises a current amplifying device comprising a first, second and third amplifier connected in cascade. The current from the third amplifier forms the output current of the current amplifying device. The current from the first amplifier subtracts from the current provided by the third amplifier, and the current from the second amplifier operates as a rectifier and outputs its current onto a power supply terminal. The power supply terminal is decoupled from ground via a capacitor. Another embodiment of the telephone line current amplifier comprises only two amplifiers if less severe distortion ratios are imposed.

Abstract: The ring relay control unit of an FXS includes a main control unit for controlling relay interrupt command; a relay control device for generating a relay control signal in accordance with a relay interrupt command transferred from the main control unit, an SLIC for interfacing a call signal to a subscriber's phone, a ring signal generator for generating a ring signal transferred to the subscriber's phone, and transferring a synchronous signal, which generates a relay control signal, to the relay control device, and a relay for selectively transferring the call signal and the ring signal to the subscriber's phone from the SLIC and the ring signal generator.

Abstract: The invention provides an apparatus for use with a subscriber line interface circuit in a telephone system, the subscriber line interface circuit being interposed between a telephone central office and a subscriber line, the subscriber line being coupled with a subscriber telephone device.

Abstract: An automatic power supplying device for providing power for a CPU of a telephone to activate the CPU and wake up a downstream circuit including for example a speech processor, a voice amplifier, etc., is disclosed. The automatic power supplying device includes a recharging circuit providing the power for the CPU for a predetermined period when there is a coining phone call and the telephone is hooked off. After the predetermined period, the CPU is supplied thereto power which is transmitted along the telephone line and accompanies the phone call signal. The CPU of the telephone is activated only when the telephone is in a hook-off state according to the present invention so that the life span of the CPU can be extended, compared to the conventional telephone.