Abstract: The three-phase synchronous rectifier for battery charger on board vehicle comprises: three rectification units provided with respective inputs connected to respective phases of a permanent magnet generator and with respective outputs connected to a battery of a vehicle; wherein the rectification units are configured to receive at input respective phase currents of the generator and to supply at output rectified currents; and wherein each of the rectification units comprises a current sensor connected to a respective phase of the generator and a respective output circuit connected to the battery and operatively connected to said current sensor; the current sensor being configured to receive at input a respective phase current and the output circuit being configured to be piloted by means of the current sensor to generate the rectified currents; wherein the current sensor comprises at least one toroidal element made of a magnetic material crossed by a lead which conveys the phase current and at least one Hall

Abstract: An example AC/DC phone line detection system may include one or more of an electronic circuit that is floating with reference to ground, a first A/D converter coupled to the electronic circuit and configured to detect ringing voltages from DC voltages included in a telephone line, a second A/D converter coupled to the electronic circuit and configured to detect caller identification information from AC voltages included in the telephone line, and a processor configured to control signals detected by the first and second A/D convertors and output information about the signals to call taking equipment.

Abstract: A surge protection device for providing bidirectional detections of one or more surge events. The device has low dynamic resistance during a surge protection mode, and it conducts ultra-low leakage current outside of the surge protection mode. In one implementation, the device includes first and second power transistors, a sensing circuit, and a driver circuit. The first power transistor includes a first source terminal that is coupled to the substrate, and the second power transistor includes a second source terminal that is coupled to the substrate. The sensing circuit is configured to detect a voltage of the first pin relative to the second pin and generate a sense signal when the voltage exceeds a threshold. The driver circuit is configured to generate a driver signal based on the sense signal and output the driver signal to at least one of the first or second gate terminal.

Abstract: A computing device includes a module that connects to a main board and a short detector. The short detector applies a voltage to a first electrical contact of the module; while the voltage is applied: makes a comparison of a second voltage on a second electrical contact of the module to the voltage; makes a determination, based on the comparison, that the first electrical contact is connected to the second electrical contact via a short circuit; and in response to the determination, initiates remediation of the short circuit.

Abstract: Memory short detection systems and methods include a power supply system with first power rail. A memory system includes a memory device connector that is configured to couple to a memory device and includes a first pin that is coupled to the first power rail and a second pin located adjacent the first pin. A short detection circuit is coupled to the first pin. The short detection circuit is configured to provide a first voltage from the first power rail, compare the first voltage to a first short detection voltage, and determine whether a short exists across the first pin and the second pin based on the comparing of the first voltage to the first short detection voltage. If a short is determined to exist across the first pin and the second pin, power is prevented from being provided to the memory device connector.

Abstract: A network powered device includes field effect transistors connected as bridge circuit. The bridge circuit includes control circuitry to enable the FETs based on completion of a powered device detection sequence performed by power sourcing equipment coupled to the device via an Ethernet link.

Abstract: A compensation circuit connected to an accelerometer's output extends the frequency response of the accelerometer, while reducing noise produced by the accelerometer. The compensation circuit has a gain as a function of frequency that is (i) constant up to a first frequency that is less than the accelerometer's natural resonance frequency, and (ii) reduced to approximately zero at a second frequency that is greater than the accelerometer's natural resonance frequency.

Abstract: Provided are an electronic patch device, network system, and operation method in the network system. The network system includes n (n is a natural number equal to or greater than 1) network equipments, a backup network equipment used for backing up one of the n network equipments, n terminals connected to the n network equipments respectively, and a distributor connecting respective lines between the n network equipments and the n terminals and replacing one of the n network equipments with the backup network equipment according to necessity. Here, a plurality of the distributors are connected in parallel.

Abstract: A disposable absorbent article worn about the lower torso of a wearer includes at least one pair of side panels connecting a first waist region to a second waist region forming a waist opening and a pair of leg openings. Each side panel includes a waist region, a hip region and a leg region wherein the waist region, the hip region and the leg region differs structurally, functionally and visually to provide an improved initial fit and sustained fit while exhibiting a garment-like appearance.

Abstract: In one embodiment, a low cost, simple circuit for detecting an off-hook condition of a telecommunication line comprising tip and ring signal lines is provided. The circuit comprises a voltage divider for coupling between the tip and ring lines without an intervening transistor and having a node at which is presented a scaled version of a voltage across the voltage divider. The circuit further comprises a transistor having a control terminal coupled to the node, a first current flow terminal coupled to a voltage source, and a second current flow terminal coupled to an output terminal, wherein the output terminal bears a value that is indicative of a voltage across the tip and ring lines and thus whether the telecommunication line is off-hook.

Abstract: This invention provides a communication apparatus, which suppresses abrupt changes of a current and voltage generated in a communication line upon connecting an external telephone to the communication line, and a control method thereof. To accomplish this, in a communication apparatus of this invention, when an off-hook state of an external telephone is detected upon connecting the external telephone to a communication line, an SOC captures a line using a first line capture means having an impedance lower than the external telephone side, and then switches an H-relay to connect the external telephone to the communication line. Furthermore, the SOC temporarily switches a line capture state to a second line capture means having an impedance higher than the first line capture means after the H-relay is switched and before the line is released.

Abstract: A method and apparatus is provided for ring-trip detection in a line card having an analog-to-digital converter for processing voice signals. The method includes receiving a ringing control signal, transmitting a ringing signal to a subscriber line in response to the ringing control signal, and receiving a portion of the ringing signal from the subscriber line. The method includes converting the portion of the ringing signal to a digital signal using the analog-to-digital converter, and providing a ring-trip indication in response to the digital signal. The apparatus includes first circuitry capable of processing a voice signal, the circuitry including a analog-to-digital converter for processing the voice signal. The apparatus includes a ringing generator, second circuitry, and ring-trip detection logic. The generator is capable providing a ringing signal to a subscriber line in response to receiving a ringing control signal.

Abstract: The invention relates to a method and to a device for testing the function for inverting the polarity on a subscriber connection line (TAL) comprising several wires (a, b), in order to connect at least one subscriber to a subscriber connection line (SLM), which comprises at least one inverting device (RG) and a current measuring device (MG) which is associated with the inverting device (RG). In a first step, the subscriber connection component (SLM) is separated from the inverting device (RG) and forces physical inversion on the wires (a, b) of the subscriber connection line (TAL). In a second step, the inverting function of the inverting device (RG) is activated. In a subsequent third step, the subscriber connection component (SLM) is separated from the device (DC) which forces the physical inversion and is connected to the inverting device (RG). The correct function of inversion is tested during all three steps by measuring the direction of the current flow.

Abstract: A system and method is disclosed for verifying a commercial transaction between a card-holder, a merchant, and a credit card company. The card-holder makes a purchase with the merchant using a full credit card number. The merchant submits a transaction approval request for approval with the credit card company. The credit card company executes conventional credit approval of the transaction approval request, as well as verifies the transaction approval request with the card-holder. An approval is sent to the merchant only after the transaction approval request is both conventionally approved by the credit card company and verified by the card-holder. The card-holder, or the credit card company, may initiate verification of the transaction approval request. The transaction approval request can also be automatically verified if one or many pre-verification criteria is/are satisfied by data contained in the transaction approval request.

Abstract: A hook switch turns on a transistor by connecting the positive electrode terminal of a capacitor to a base terminal of a transistor in an off-hook state, causing a speech circuit and telephone lines to be connected. The hook switch turns off the transistor by disconnecting the positive electrode terminal of the capacitor from the base terminal of the transistor in an on-hook state, causing the speech circuit and the telephone lines to be disconnected. A holding circuit holds the voltage at the positive electrode terminal of the capacitor at a substantially fixed value by charging the capacitor with electric power supplied from the telephone lines in an off-hook state.

Abstract: The invention relates to methods for testing analog telephone line equipment including, in particular to detect faults in their hybrid resistor arrays. It consists in isolating the equipment from the telephone line and then applying the normal ringing signal to it. If the resistor array is defective, the output logic signal of the off-hook/on-hook detector circuit comprises a succession of 0 and 1 at the frequency of the ringing signal, which indicates the fault. This makes it possible to eliminate the equipment test relay usually employed.

Abstract: 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 and the second lead to a ring wire. A diode bridge is coupled to the first lead and the second lead had a positive output. A low side switch is coupled to the positive output of the diode bridge without a high side switch between the low side switch and the positive output of the diode bridge.

Abstract: A subscriber line interface circuit apparatus includes a signal processor having sense inputs for sensed tip and ring signals of a subscriber loop. The signal processor generates linefeed driver control signals in response to the sensed signals. A linefeed driver provides the sensed tip and ring signals. The linefeed driver drives the subscriber loop in accordance with the linefeed driver control signals.

Abstract: A method and structure for cutting a ring current when a telephone enters an off-hook state. The method includes: (1) activating an off-hook detected signal when the telephone enters an off-hook state, (2) applying the off-hook detected signal to a selected input terminal of a coder/decoder (CODEC), (3) storing configuration information in the CODEC identifying the selected input terminal and a selected output terminal of the CODEC, (4) activating a ring cut control signal on the selected output terminal in response to the activated off-hook detected signal and the configuration information, and (5) cutting the ring current in response to the activated ring cut control signal. The CODEC includes a control register for storing the configuration information, and a hardware cut ring current (HCRC) circuit, which activates the ring cut control signal on the selected output terminal in response to the activated off-hook detected signal and the configuration information.

Abstract: A voice messaging system such as a telephone answering device which allows a calling party to bypass the ring signal and substantially immediately allow the calling party to leave a voice message. To activate the no ring signal access to the telephone answering device, the calling party preferably enters a control sequence prior to entering the telephone number of the called party to signal the appropriate central office to signal the telephone line of the called party that the ring signal is to be bypassed. The central office includes an appropriate ring signal bypass request detection module adapted to detect a request for no ring signal from a calling party. In the disclosed embodiment, the calling party signals the central office using an appropriate sequence of DTMF tones, e.g., ‘*77’, and the central office in turn signals the telephone line using a non-ring signal, e.g., a line reversal.

Abstract: Subscriber line interface circuitry includes an integrated circuit having sense inputs for a sensed tip signal and a sensed ring signal of a subscriber loop. The integrated circuit generates a subscriber loop linefeed driver control signal in response to the sensed signals. The linefeed driver does not reside with the integrated circuit. A method for monitoring power dissipation of the linefeed driver components includes the step of sampling at least one of the tip and ring signals to determine a line voltage and a line current of a selected linefeed driver component. Instantaneous power dissipation of the linefeed component is estimated and then filtered to generate an estimated junction temperature of the linefeed component. In one embodiment, the linefeed driver includes a tip fuse series-coupled to the tip line and a ring fuse series-coupled to the ring line.

Abstract: 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 ring wire. A diode bridge is coupled to the first lead and the second lead and has a positive output. A low side switch is coupled to the positive output of the diode bridge without a high side switch between the low side switch and the positive output of the diode bridge.

Abstract: A system and a method selectively switch between two different voltage supplies supplying a common node. A first of the voltage supplies is coupled to the common node by a first switch and a second of the voltage supplies is coupled to the common node by a second switch. The switching device comprises: a feedback network comprising a high-pass filter for filtering a signal at the common node and outputting the filtered signal as a feedback signal; a timing controller coupled to at least one of the first and second voltages supplies for determining when to switch between said first and second power supplies; a ring switch controller for applying a first control signal to the first switch for selectively enabling and disabling the first switch in response to the timing controller and the feedback signal; and a battery switch controller for applying a second control signal to the second switch for selective enabling and disabling the second switch in response to the timing controller and the feedback signal.

Abstract: A method (10, 20) and apparatus (30) enables a customer (47) to distinguish between a dead or broken Internet Protocol telephone line and an out-of-service Internet Protocol telephone line. The method detects (11) a hook status of a device (46) coupled to the IP network (33) during an out-of-service status of the line. Upon detection of a change in state from an on-hook state to an off-hook state, a message is sent (13) to the device (46) indicating that the IP telephone line is currently out-of-service and not dead or broken. This message can be a voice or text message. Moreover, the message can provide status information for all of the interfaces of the device coupled to the IP telephone line. In addition, the message can include information as to how to obtain service, such as a telephone number to call.

Abstract: An object of this invention is to provide a method and a device for easily connecting and disconnecting a telephone communication line using an auditory organ instead of using a complex mechanism component. A distance between a speaker and the auditory organ of a telephone call receiver or a telephone call transmitter is detected using acoustic impedance and reflective wave properties of the auditory organ of the telephone call receiver or the telephone call transmitter to control call operations such as connection and/or disconnection of a communication line.

Abstract: A detection circuit and method for detecting AC voltage pulses at a defined frequency relate to first transforming an input signal to a low-frequency signal by multiplying the input signal by a mixing frequency. This down-mixed signal can then be filtered and evaluated. The circuit is particularly suitable for identifying charge unit signals in the telephone network.

Abstract: A network interface circuit that screens out transient signals and provides an indication to the line side that an actual event has occurred, so that appropriate discrimination circuitry is powered up to determine the exact nature of the actual event only when actually needed. The present invention develops an AC signal that represents the events that are desired to be detected. This AC signal is timed so that it has a sustained rate (e.g., a 1 millisecond burst) that is unlike any transient that would occur on the line. Thus, unless the incoming signal meets the timing requirements of the circuit, it is disregarded as a being a transient and no action is taken to determine the exact nature of the signal. This avoids the need to invoke the discrimination circuits that have large power requirements until they are actually needed.

Abstract: The invention herein is fallback function communications device comprised of a microprocessor, utilized to perform a predetermined operation and processing of a predetermined input signal and then output a corresponding signal, as well as a minimum of one relay circuit having an amplifier circuit and a relay. The terminal at the first side of the relay is connected to the telephone line tip/ring terminal, while the terminal at the second side of the relay is connected to the Public Services Telephone Network (PSTN) tip/ring terminal of the microprocessor. An off-hook detection circuit is connected to the PSTN tip/ring terminal and also connected to the ring detection terminal of the said microprocessor. A dummy load circuit is connected to the tip terminal and the ring terminal of the PSTN. As such, in the event of Voice Over Internet Protocol (VOIP) system failure, the present invention is capable of automatically switching to the PSTN and thereby maintain telephone system operation.

Abstract: A PNPN structure thyristor and a third P-type impurity region are formed on a semiconductor substrate, and a fixed current circuit using an NPN transistor 20 and a resistor 30 is connected to a cathode terminal K and a gate terminal G of a composite element 10 that has a P-channel MOS transistor Q3 with the third P-type impurity region as a drain connected to a PNP transistor Q1 of the thyristor. If a voltage applied to the anode terminal A of the composite element 10 rises from 0V, initially the thyristor is on and current flows, but once the threshold voltage of transistor Q3 is reached transistor Q3 turns on. A short circuit then exists between the base and emitter of transistor Q3 of the thyristor and current of the composite element 10 itself is cut off. Because of the bipolar structure it is simple to configure a small integrated circuit with a high withstand voltage.

Abstract: A ring boost circuit has a first switching device coupled to a ring node. The first switching device is responsive to a ring operation. A charge pump is connected to the ring node, and the charge pump provides a voltage offset to enhance a differential voltage between the ring node and a tip node when the first switching device is activated during the ring operation.

Abstract: A subscriber line interface circuit apparatus includes a signal processor having sense inputs for sensed tip and ring signals of a subscriber loop. The signal processor generates linefeed driver control signals in response to the sensed signals. The signal processor resides on an integrated circuit die. In another embodiment, a subscriber line interface circuit apparatus includes a signal processor generating subscriber loop control signals in response to sensed tip and ring signals from the subscriber loop. A linefeed driver portion drives the subscriber loop in accordance with the subscriber loop control signals. The linefeed driver portion provides the sensed tip and ring signals. Each of the linefeed driver portion and the signal processor resides on an integrated circuit die. In one packaging implementation, the signal processor and the linefeed driver portion reside on separate integrated circuit die within separate integrated circuit packages.

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 circuit for closing a relay when an active AC voltage connected to one of the contacts of the relay is approximately zero volts includes a monitoring circuit that monitors the active AC voltage and outputs a phase-shifted voltage that crosses zero volts at predetermined times before the active AC voltage traverses zero volts. A pulse generating circuit initiates a pulse when the phase-shifted voltage enters a predefined voltage region and terminates the pulse when the voltage exits that region. An input signal is strobed onto the control input of the relay by the pulse so that the relay changes state coincident with the zero crossing of the active AC voltage.

Abstract: An interface circuit including a galvanic isolation barrier between a transmission line and a user equipment, and a detector for detecting, independently from a transmission, the idle or busy state of the line.

Abstract: 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 same as a corresponding portion of an input sequence of decoded data obtained from a low bit-rate speech decoder. The input sequence has at least one distorted non-voice sequence. The method provides for inserting a substantially undistorted non-voice sequence into the output sequence, the undistorted sequence being at least of substantially the same length as the distorted sequence, a portion of the output sequence following the undistorted sequence being the same as a corresponding portion of the input sequence, and the output sequence being substantially free of the distorted non-voice signal.

Abstract: A method and apparatus for measuring signals conveyed by a varying polarity voltage signal across a tip and ring in a telephone system is disclosed. A voltage present across the tip and ring is used to charge a charge storage device, and the charge is periodically discharged for a relatively short amount of time. The burst of discharge current for the short amount of time allows an optocoupler to accurately operate, while presenting a very high impedance to the telephone line.

Abstract: 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 decoupling of a POTS channel from one or more xDSL channels on a telephone connection (subscriber loop associated with a public service telephone network), while reducing undesirable interference, such as intermodulation distortion imposed upon the POTS and xDSL channels. Transistors associated with the polarity guard are operated in the ohmic region, or in a nonsaturated linear mode, to achieve a substantially linear transfer function through the transistors and through the overall linear polarity guard. Current that is input to the polarity guard and the voltage drop across the transistors that conduct the current in the polarity guard exhibit a substantially linear relationship, or linear VI transfer function.

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: To secure an ADSL connection between a first ADSL transceiver (4) in a central office and a second ADSL transceiver (5) on a subscriber's premises on a telephone line (1) between a SLIC (2) in the central office and a telephone (3), a request to the SLIC (2) to apply a ringing signal to the telephone line (1) is detected. In response to such detection, the first ADSL transceiver (4) switches from a normal bit rate to a lower bit rate for the ADSL connection, and orders the second ADSL transceiver (5) to do the same before the ringing signal is applied. In response to an off-hook condition, the lower bit rate is maintained for the ADSL connection. In response to an on-hook condition after the off-hook condition as well as in response to a disappearance of the ringing request without an off-hook condition, the first ADSL transceiver (4) switches back to the normal bit rate and orders the second ADSL transceiver (5) to do the same.

Abstract: A telephone signal detecting circuit is provided, which can identify an input signal is a line reversal signal or a ring signal. Providing this telephone signal detecting circuit into a ring detector of a conventional telephone set can share the burden of the microprocessor of the telephone set and lessen the loading of power supply. In this invention, the Schmitt triggers of two different trigger levels are used to respectively detect the voltage change of the first discharge of the capacitor and the ripple signal produced due to the charge of the capacitor by the ring signal. The input signal can be easily identified to be a line reversal signal or a ring signal through a simple flip-flop circuit that can reduce the influence of the bouncing effect. The telephone signal detecting circuit is operated in a static mode and is almost free of power-consumption when it is not working.

Abstract: 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. The telephone system includes an A/D converter for making A/D conversion of the line input signal such as a CPC signal, a bell signal, and a usage state signal indicating a telephone line usage state to output a digital line input signal, and a frequency analyzing unit for making frequency analysis of the digital signal converted by the A/D converter, and the central processing unit judges the kind of the line input signal based on a result of the frequency analyzing unit.

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 PNPN structure thyristor and a third P-type impurity region are formed on a semiconductor substrate, and a fixed current circuit using an NPN transistor 20 and a resistor 30 is connected to a cathode terminal K and a gate terminal G of a composite element 10 that has a P-channel MOS transistor Q3 with the third P-type impurity region as a drain connected to a PNP transistor Q1 of the thyristor. If a voltage applied to the anode terminal A of the composite element 10 rises from 0V, initially the thyristor is on and current flows, but once the threshold voltage of transistor Q3 is reached transistor Q3 turns on. A short circuit then exists between the base and emitter of transistor Q3 of the thyristor and current of the composite element 10 itself is cut off. Because of the bipolar structure it is simple to configure a small integrated circuit with a high withstand voltage.

Abstract: A line card for coupling to customer premises equipment at a termination for detecting hook condition in a telephone system, the line card comprising an interface for transmitting and receiving an analog signal with the telephone line, an AC ring signal generator for generating a ring signal at the customer equipment, a DC signal generator for generating a DC signal when said customer equipment is off hook, and a circuit for determining the duty cycle of a loop current in the customer equipment (telephone) for determining the hook status of the customer equipmen.

Abstract: A ring trip detector circuit and method for use with a plurality of subscriber line interface circuits each having at least one telephone unit connected to it, having a ring generator for feeding a ringing voltage to the subscriber line interface circuits, and which detects when at least one of the subscriber units goes off-hook. The voltage level of the ringing voltage is compared with a predetermined level so as to detect when any one of the ringing subscriber telephone units goes off-hook. Thereafter, each of the plurality of subscriber line interface circuits is sequentially disconnected from the ring generator, and reconnected only in the absence of an off-hook condition in the disconnected subscriber telephone unit. The ringing voltage thereby remains fed to all ringing subscriber lines for which all connected equipment is on-hook.

Abstract: A telephone ring signal detector is coupled to a telecommunication line for detecting a first telephone ring signal, and for discriminating the first telephone ring signal from other line signals on the line. This detector comprises an event generator, coupled to the line, for receiving an incoming signal and for generating an initial event signal and an ending event signal, and a signal characteristic generator, coupled to the line and to the event generator, for generating a signal characteristic of the incoming signal after the initial event signal. This detector further comprises a signal characteristic limit device, for generating a predetermined signal characteristic range limit of the first telephone ring signal, and a signal characteristic comparator coupled to the signal characteristic generator, to the signal characteristic limit device and to the event generator, for comparing the signal characteristic with the predetermined signal characteristic range limit.

Abstract: A cleaning system retrieves a telephone number from a telephone number list to regard as a called party number and sends a SETUP message to the network, in which a SPEECH or an AUDIO is designated as a bearer capability. In case that an ALERTING or CONNECT message is sent back from the network, the system sends a DISCONNECT message to the network immediately to perform a clear sequence and determines the telephone number effective. In case that a DISCONNECT message is sent back from the network as a result that a call has not been accepted, the system also performs a clear sequence immediately and determines if the telephone number should be treated as an effective number or a null number according to the cause content sent from the network.

Abstract: The telephone line coupler circuit has a single transmit opto-coupler whose output includes a DC bias component connected to a gate of a line seize switch for connecting a DC line seize load across the ring and tip contacts of the telephone line. The line seize switch is saturated by the transmit opto-coupler bias output and the AC component of the transmit opto-coupler output is sent over the telephone lines. The receive opto-coupler is used both for receiving communications signal and for detecting the ring signal. The band pass filter connected to the output of the receive opto-coupler may be switched to pass a ring signal frequency band or a communications frequency band. The circuit operates using two opto-coupler devices while conventional circuits require four opto-coupler devices.

Abstract: The telephone line coupler circuit has a single transmit opto-coupler whose output includes a DC bias component connected to a gate of a line seize switch for connecting a DC line seize load across the ring and tip contacts of the telephone line. The line seize switch is saturated by the transmit opto-coupler bias output and the AC component of the transmit opto-coupler output is sent over the telephone lines. The receive opto-coupler is used both for receiving communications signal and for detecting the ring signal. The band pass filter connected to the output of the receive opto-coupler may be switched to pass a ring signal frequency band or a communications frequency band. The circuit operates using two opto-coupler devices while conventional circuits require four opto-coupler devices.

Abstract: The invention herein is fallback function communications device comprised of a microprocessor, utilized to perform a predetermined operation and processing of a predetermined input signal and then output a corresponding signal, as well as a minimum of one relay circuit having an amplifier circuit and a relay. The terminal at the first side of the relay is connected to the telephone line tip/ring terminal, while the terminal at the second side of the relay is connected to the Public Services Telephone Network (PSTN) tip/ring terminal of the microprocessor. An off-hook detection circuit is connected to the PSTN tip/ring terminal and also connected to the ring detection terminal of the said microprocessor. A dummy load circuit is connected to the tip terminal and the ring terminal of the PSTN. As such, in the event of Voice Over Internet Protocol (VOIP) system failure, the present invention is capable of automatically switching to the PSTN and thereby maintain telephone system operation.