Abstract: The ADSI system 100 has a file stored in RAM 202 or ROM 204. The file plays a CAS tone. The CAS tone is disguised by playing one or more introductory tones as frequencies lower than the CAS tone. The user is conditioned to receive a CAS tone by ramping the CAS tone amplitude or increasing the amplitude in discrete steps.

Abstract: A telephone exchange transmits audible signals to a subscriber line to indicate exchange or network conditions. The audible signals to be transmitted to the subscriber line are selected from one or more available audible signal sources according to the contents of a store location for that subscriber line. Further store locations are provided for each subscriber line to enable selection of further audible signal sources dependent upon the condition. The subscriber may alter the contents of his or her store location by dialing a special code.

Abstract: A power converter forming part of a telephone subscriber line interface circuit selectively generates a ringing signal waveform, for supply to the line, or a supply voltage for a driver circuit for providing loop current on the line. First and second fixed frequency PWM signals are used to control the power converter, and hence the voltage which it generates, for the ringing signal waveform and the supply voltage respectively. The first PWM signal enables the power converter to provide a high power level needed for ringing signals. The second PWM signal has a lower frequency, and hence results in lower switching losses and power dissipation, and a lower duty cycle, suitable for the lower power level needed for the supply voltage, and is conveniently produced by masking pulses of the first PWM signal. The frequency of the second PWM signal is greater than 270 kHz, to avoid transmitting spectral energy to the line below this frequency.

Abstract: A method is described for electronically recording messages after the called telephone goes off-hook. The method may be physically implemented by an apparatus in the home or office, or by a system installed in a service provider central office. When a call is received, the telephone receiver is taken off the hook and the caller is asked if they would like to leave an electronic message. If the caller decides to leave an electronic message, the record function is initiated by the answering party via a record button physically provided on the system, by a keystroke sequence on the telephone station set keypad, or by voice command. The message speech is sampled, each sample is processed to extract speech information, each extracted signal is encoded, and then each encoded signal is stored in memory.

Abstract: In response to an incoming call connection request, a terminal type associated with a called party subscriber terminal is communicated back from a terminating exchange to an originating exchange. The originating exchange then instructs the terminating exchange to provide a particular ring tone (distinctive ring) associated with the determined terminal type over an established call connection. The terminating telecommunications then generates the instructed ring tone over the call connection and waits a predefined period of time before alerting the called party subscriber terminal. Upon hearing the distinctive ring tone, the calling party subscriber is able to ascertain the dialed terminal type (business, residential, cellular, wireline) and has an option to terminate the established call connection before the called party subscriber is alerted.

Abstract: A method and apparatus for testing a customer premises equipment (CPE) alert signal detector used to detect the start of a Caller ID data transmission using test CPE alert signals generated by a testing platform and mixed with a voice signal as an input to the detector. The testing platform also generates a special sync signal which is input to control circuitry connected to the CPE alert signal detector. An active sync signal indicates when a valid CPE alert signal should be detected. The control circuitry is configured to execute a test algorithm that monitors both the sync signal and the output of the detector and indicates when the CPE alert signal detector has validly detected a CPE alert signal, falsely detected a CPE alert signal, or failed to detect a CPE alert signal. The number of valid, false, and missed CPE alert signal detections are totaled and can be used to calculate the talkoff and talkdown error rates for the detector.

Abstract: A technique for selectively storing as a selected ring one of various rings programmed in a ROM within a controller of a telephone which has a controller for storing a program for various rings therein, an output key for confirming the stored rings, and a selection key for selecting a ring, the technique including the steps of: storing as a selected ring one of the rings stored in the controller; and transmitting the selected ring stored in step in response to a call signal being inputted.

Abstract: An apparatus for detecting customer premise equipment alerting signals (CAS) in a first telephone having a transmit circuit and a receive circuit and a hybrid line termination for connecting the transmit circuit and the receive circuit to a central office line. The apparatus includes an off-hook detector for producing an off-hook signal identifying whether or not the first telephone is in an off-hook state, an extension-in-use detector for producing an extension-in-use signal identifying whether or not a second telephone connected to the central office line is in an off-hook state, a CAS detector selectively operable to receive the CAS signals directly from the central office line and from the hybrid line termination and a control element for controlling the CAS detector in response to the off-hook signal and the extension-in-use signal.

Abstract: A telephone ringing signal generator includes a DC converter for producing high positive and negative voltages that define peak amplitudes of the ringing signal, which is produced by low pass filtering a generally trapezoidal waveform having these peak amplitudes. The generally trapezoidal waveform is produced by a level-shifting integrator at a frequency determined by a low voltage square wave supplied to the integrator. The integrator comprises a capacitor coupled between a virtual ground point and an output of the integrator and arranged to be charged with two opposite polarities in response to opposite transitions of the square wave, and a resistor via which the square wave is supplied to the virtual ground point. Buffers are provided for buffering the trapezoidal waveform supplied to, and the ringing signal produced by, the low pass filter.

Abstract: A telephony call waiting feature is provided wherein a caller ID information related to a third party wishing to converse with a first party already engaged in a conversation with a second party is provided to the first party. When the local office sends an alerting tone (e.g., CAS) to the first party, the first party telephone set responds by attenuating signals going to the first party handset. The local office then transmits the caller ID information relating to the third party and the first party apparatus receives and displays to the first party the caller ID information related to the third party thereby allowing the first party to either accept or reject the waiting call based on the displayed information.

Abstract: A telephone call alerting system is applied to a telephone communication system accommodating a line to which a telephone terminal is connected, a plurality of telephone numbers being assigned to the line.

Abstract: A message waiting notification system comprising a telephone provider's off premise central switching office connected to a Dual Signal Triggered Message Waiting Indicator (DSTMWI) circuit via a telephone line is disclosed. The central switching office transmits predetermined asynchronous Frequency Shift Keying (FSK) signals and/or audible tones indicating different types of electronically stored communication messages awaiting retrieval, such as voice mail, E-mail, fax mail and video mail. Responsive to receiving the FSK signals and/or audible tones from the central switching office via the telephone line, the DSTMWI circuit provides visual notification of any combination of different types of the electronically stored communication messages.

Abstract: A communications device is presented which is able to detect a ring signal without the need for dedicated ring signal detection circuitry. The communications device includes a hookswitch coupled between a telephone line and a communications circuit. In an open mode of the hookswitch, an electrical resistance of at least 25 megohms exists between two switch terminals of the hookswitch, and the communications circuit is essentially disconnected from the telephone line at d.c. A capacitor positioned between the switch terminals of the hookswitch couples a.c. signals from the telephone line to the communications circuit when the hookswitch is in the open mode. A DSP of the communications circuit performs ring signal detection when the hookswitch is in the open mode using electrical power provided by a power supply. The input impedance of the communications circuit is substantially equivalent to a series combination of an inductance and a resistance.

Abstract: A keyset that connects to telephone switches via analog lines, wherein a processor in the keyset communicates with the switch via in-band signaling to provide keyset functionary. When a call comes into the switch for one of the directory numbers (DNs) associated with the keyset, the switch sends a frequency shift key (FSK) encoded message to all of the keysets associated with that DN. The FSK message includes at least the DN of the terminating telephone line, and may also include an extension number or other code. The processor in the keysets receives the message, decodes it, and then alerts the users of the incoming call.

Abstract: A communication apparatus in accordance with the present invention determines the origin of an incoming telephone communication based on the calling party's number. When a call is made to a communication line to which an apparatus of the present invention is connected, the apparatus determines the number of digits in the calling party's number, and uses a ringing pattern or tone to indicate the source of the incoming call to the called party.

Abstract: A telephony system includes a plurality of local network terminations connected to a street cabinet in turn connected to an exchange. The street cabinet has a power supply for supplying voltage, a clock for generating a master ringer signal, and a modulator for modulating the voltage with the ringer signal. The filters extract the DC voltage and the ringer signal. The extracted DC voltage and the extracted ringer signal obviate the prior art requirements to provide a separate DC power supply and a separate clock within each local network termination, thereby avoiding duplication of components within each local network termination.

Abstract: A telephone line interface circuit comprises a controlled voltage generator for selectively generating a ringing voltage waveform for a telephone line or a supply voltage for a drive circuit for the telephone line, and a switching circuit interconnecting an output of the controlled voltage generator, the drive circuit, and the telephone line accordingly. In order to avoid creating a potentially hazardous condition on the telephone line, an interlock is provided between enabling of the controlled voltage generator and switching of the switching circuit, and software and hardware monitoring functions monitor operation of the control software and the controlled voltage generator and disable the controlled voltage generator in response to fault conditions or unusual behavior.

Abstract: Telephone communications systems and methods are provided enabling subscribers to establish an easily changed plan for call completion, over an Advanced Intelligent Network to any of several alternative locations, of calls dialed to a single directory number. A call to the same directory number by an authorized caller can enable the caller immediately to update the call completion plan dependent on the caller's status. A distinctive ringing signal is applied on a per-call basis to calls completed under the call completion plan. The call completion plan is maintained as a part of a call processing record at an ISCP.

Abstract: A telephone set including a data obtaining device which obtains a plurality of sets of own-call-number data each set of which identifies a corresponding one of a plurality of different own call numbers allotted to the telephone set according to a common numbering rule, each of the different own call numbers identifying the telephone set from other telephone sets to which other call numbers different from the own call numbers are allotted according to the common numbering rule, a plurality of memories which are related with the different own call numbers, respectively, and in which a plurality of batches of sound information are stored, respectively, and a transmitter which transmits, to one of the other telephone sets, the batch of sound information stored in one of the memories which corresponds to one of the different own call numbers identified by one of the sets of own-call-number data obtained by the data obtaining device.

Abstract: A circuit and method for reducing power consumption during operation of a solid state switch that controls connection of a source of alternating current to a load includes a circuit for determining a voltage across the switch. The switch is operated upon receipt of both a command signal and an indication that the voltage across the switch is less than a predetermined value. When used in a telephone system subscriber line interface circuit (SLIC), the circuit controls two switches that connect an ac ring signal from an ring generator to a telephone. The voltage sensed across the switch may be converted to a low current level and the circuit embodied in an integrated circuit.

Abstract: An apparatus for determining a power cross condition during a ringing state of a telephone. The apparatus also is capable of distinguishing a true power cross condition from a short loop ringing condition, by including a first path for receiving a signal indicative of a voltage across a ring feed resistor exceeding a predetermined value, and determining if that voltage is in an active state for a predetermined amount of time (i.e., 14 milliseconds). The apparatus also includes a second path for receiving a first and second current that flow respectively across a first and second sense resistor connected to opposite ends of the ring feed resistor. On the second path, the first and second currents are subtracted, converted to a digital value, filtered, and compared to a threshold value to determine if a ring trip has occurred. If so, the potential ring trip is sent to a persistence timer circuit, for checking if it is in an active state for a predetermined amount of time (i.e., 104 milliseconds).

Abstract: A cellular communication network (10) and method operates at frequencies above 2 GHz and achieves widespread coverage within a cell (14) by adapting routing channels, symbol rates, and FEC coding processes (78) to current RF broadcast conditions. A portion of subscriber nodes (16) act as repeaters for a base node (12). If subscriber nodes (16) cannot directly communicate with the base node (12), their communications may be indirectly routed to the base node (12) through one or more repeating subscriber nodes (16'). If current conditions do not support a high data rate, then lower data rates are supported by selection of FEC coding processes (78). If increasingly inclusive FEC coding does not achieve a data rate supportable by current conditions, slower symbol rates may be used. Communications at slower symbol rates may utilize narrower frequency bands thus keeping wider frequency bands available for higher speed usage.

Abstract: A system and method for modifying a composite Ring AC/Message Waiting (RAC/MW) signal to prevent bell tap on analog telephones. The composite RAC/MW signal comprises AC signals and DC signal alternately spaced in time. At a zero crossover point the composite RAC/MW signal is ramped from a given bias voltage level to a desired Message Waiting voltage level at a slope sufficient to prevent bell tap. Near the end of the Message Waiting portion of the composite signal the composite signal is ramped to the bias voltage level at a slope sufficient to prevent bell tap.

Abstract: An alerting cadence control system for a telephone network having a telephone exchange, subscriber transmission equipment connected to the telephone exchange, and a plurality of telephone sets each connected to the subscriber transmission equipment. The subscriber transmission equipment includes a plurality of subscriber interface cards and subscriber-shared alerting cadence control means, each of the cards incorporating a switch for performing alerting cadence switching of each telephone set. The subscriber-shared alerting cadence control means has a memory for control setting data in the format of a table in which is written a control program for controlling the switch connected to each telephone set. Where alerting cadence control is to cover a new subscriber service offered to a new telephone set, the applicable data in the table are modified from the telephone exchange under remote control without replacement of the subscriber interface card for that telephone set.

Abstract: In methods and apparatus for providing suppressed ringing access to a subscriber line, a connection request is sent from a server to a telecommunications switch and the switch performs a connection routine in response to the connection request to connect the server to the subscriber line. The connection routine is adapted to avoid audible ringing of a telephone set connected to the subscriber line. The connection request comprises a signal indicating a subscriber line to which the server is to be connected and a signal indicating that suppressed ringing access to that subscriber line is desired. The methods and apparatus avoid the need for especially provisioned trunks between the server and the terminating switches by including in the connection request a signal indicating that suppressed ringing is desired and by making the telecommunications switch responsive to that signal.

Abstract: To generate a ringing signal by means of a subscriber line interface circuit having two final stages, each for supplying an individual subscriber line wire, one of the subscriber line wires is connected to one of the input terminals of an operational amplifier, the other input terminal of which being connected to the interconnecting point between two series connected resistors having the same resistance. The output terminal of the operational amplifier is connected, via a first resistor, to a current input terminal of the subscriber line interface circuit for generating a first current. A signal generator, via a second resistor, is also connected to said current input terminal for generating a second current. The final stages of the subscriber line interface circuit are supplied with current from current input terminal to drive the final stages to generate the ringing signal.

Abstract: A telecommunication network having a switching system connected to a called station by a line that provides notification to a called party of information relating to an incoming call. This information generally consists of the called number, but may also include an extension or other code. The called party identification is delivered to the called telephone station set during the silent period after ringing, or, advantageously, before ringing starts. A signal (e.g., FSK) is sent to the called telephone station set shortly before the ringing signal is sent to the called station. A converter at the customer premises receives the FSK signal and demodulates it. A control unit connected to the converter then causes the called DN to be displayed, may cause a distinctive ring to be made, or take other action depending upon its program.

Abstract: A method and apparatus for providing an enhanced Call Forwarding Don't Answer feature is disclosed. When an originating address calls a base address assigned the Call forwarding Don't Answer feature and the call is forwarded to a remote address, a Look Ahead feature is implemented. The Look Ahead feature determines if a call setup to a remote address is successful, unsuccessful or points out a feature assigned to the remote line. The originating address is provided with ring tone during the call setup. The call setup results are then used to make appropriate connections to implement the functions of the feature while providing a steady ring tone to the originating address.

Abstract: A system and method for accessing directory information over a telephony network employing the ADSI protocol and for presenting the directory information at the user's conventional TV monitor are described. The system includes a directory service unit, a telephony network, such as the public switched telephony network, and multiple user interface units. The directory service unit receives, processes, and stores in memory directory information from directory information providers which information is transmitted to the user interface unit of requesting users on demand. The directory service unit is connected to user interface units via the telephony network and uses the ADSI protocol to communicate data and voice signals containing directory information to users.

Abstract: A telephone terminal device, which is activated by a predetermined number of ringing signals even if a telephone call occurred immediately after a previous caller had abandoned a call before engagement of the telephone line. When the telephone terminal device is set to standby mode, the polarity of telephone line (L1, L2) is stored in microprocessor CPU-1 via photocoupler PC-3 (or PC-4) and contact y2-1. If there is a call thereafter, ringing portion of the ringing signal is detected by photocoupler PC-3 (or PC-4) via capacitor C2. During a silent period, the polarity of the telephone line (L1, L2) is checked by the aforementioned PC-3 or PC-4 via contact y2-1 which is closed. When the polarity of the telephone line at the time of abandonment of call by a caller prior to activation of the telephone terminal device coincides with the aforementioned polarity stored, the telephone terminal device is restored to standby mode (with the counter for ranging signals being cleared).

Abstract: A circuit and method for isolating a subscriber line interface circuit ("SLIC") from the ringer generator in a telephone system. The circuit uses a gain blocking device to provide a signal gain when the ringer generator is not being utilized and to provide a high impedance when a ringer signal is present. The high impedance may be provided through an amplifier circuit which is tri-stated when the amplifier is not energized.

Abstract: A user configurable telephone station receives telephone calls in a normal manner and also provides a user settable alarm for alerting a user at prescribed times. At each prescribed time, an alerting signal is provided by actuating the telephone ringer either with a distinctive ring or a normal ring, such configuration being selectable by the user. The telephone station optionally also includes a recorder with which the user may record a spoken announcements for associating with the alerting signal. When the switch-hook in the telephone station is actuated in response to the alerting signal, any associated, recorded announcements is played through an acoustic device, such as a speaker, in the telephone station.

Abstract: A telephone switching system is comprised of a main controller, switching circuits controlled by the main controller, a peripheral controller for controlling the seizing of subscriber lines for calls routed through the switching circuits, and further comprising a first memory associated with and accessible by the main controller for storing user data associated with each directory number, the user data comprising a ring type, a second memory associated with the peripheral controller for storing ringing cadence indicators associated with respective plural ring types, the main controller for reading the station data from the first memory upon receiving a request for service to a directory number, and sending the ring type indicator with a subscriber line seize message to the peripheral controller, the peripheral controller for reading the second memory and obtaining the ring cadence indicators associated with the ring type, and ringing a line according to the indicated ring cadence.

Abstract: In a ringer unit driving system for driving a ringer unit provided in common to a plurality of channel units, the ringer unit sends a ringing signal to a communications device via one of the channel units. A signaling bit detection unit, which is provided in each of the channel units, detects a signaling bit contained in a received digital signal applied to one of the channel units and generates a detection signal. A ringer provided in the ringer unit generates the ringing signal. A power source supplies the ringer with power. A switch is connected between the ringer and the power source and is connected to the signaling bit detection unit. The switch connects the power source and the ringer to each other only when the signaling bit detection unit generates the detection signal.

Abstract: The present invention relates to a method for generating the ringing tone of a phone and apparatus according to the method. A ringing tone generator (12)is controlled according to a ringing tone sequence by control circuitry (13), and subscriber identification information is stored in a fixed or a detachably connectable nonvolatile memory (10) of the phone. When the phone is switched on, the microprocessor (13) reads from a subscriber identification information memory (10) of the phone at least some of the subscriber identification information, calculates on the basis thereof the values for ringing tone parameters (1, . . . ,6) describing the ringing tone sequence, and stores them in a ringing tone parameter memory (11). When receiving a page to the phone, the control circuitry (13) reads from the ringing tone parameter memory (11) the values of the parameters (1, . . . , 6) describing the ringing tone sequence, generates a ringing tone sequence on the basis of the parameter values (1, . . .

Abstract: A hook state detector for a two-wire telephone line includes two comparators each for comparing a voltage on a respective wire of the line with a respective reference voltage, and a logic circuit or software responsive to outputs of the comparators for determining off-hook and on-hook states when one of the compared voltages is more negative and the other is more positive than the respective reference voltages, and maintaining a previous hook state determination when both of the compared voltages are more positive, and when both of the compared voltages are more negative, than the respective reference voltages. The arrangement is insensitive to common mode induced a.c. on the line. The comparators can comprise differential amplifiers or opto-couplers.

Abstract: A ringing generator includes a binary signal source generating a waveform with eight degrees of freedom controlled to suppress or cancel certain harmonics to produce a binary low frequency signal substantially free of low frequency components other than the desired ringing frequency. The binary signal is amplified and filtered to remove unwanted frequency components above a certain threshold to produce a substantially sinusoidal ringing signal.

Abstract: In a ringing signal control circuit for controlling supply of a ringing signal from a ringing signal generator to a subscriber's line in response to a call signal destined thereto, a switching element is repeatedly switched to connect the ringing signal generator to the subscriber's line under control of a switching signal from a switch controller. In order to suppress a surge voltage due to connection and disconnection of the subscriber's line for the ringing signal generator, a memory stores a time data signal representative of a transition time from a reference voltage level to an optimum voltage level for the subscriber's line. The optimum voltage level is the level at which the connection and disconnection can be carried out without generation of the surge voltage. A voltage comparator compares the ringing signal with the reference voltage to produce a coincident signal.

Abstract: A system for supervising a telephone connection using over a pulse code modulated carrier network between a first customer's equipment and a second customer's equipment. A first channel unit is located in a channel bank serving the first customer's telephone equipment. A second channel unit is located in a channel bank at a remote central office that is geographically remote from the first customer's equipment. The second channel unit is coupled to the second customer's equipment through a switch at the remote Central Office. The second channel unit includes a means for detecting a reverse battery signal generated by the Central Office when the second customer's telephone goes off-hook, and a means for converting the reverse battery signal into a digital supervisory signal. The second channel unit transmits the digital supervisory signal, preferably using the A and B signalling bits on a pulse code modulated carrier system.

Abstract: A circuit assembly which includes an interface circuit between a subscriber line and exchange devices of the kind with two amplifiers connected in a bridge configuration between the battery terminals and having a means of detecting the output currents; a supply circuit which includes the exchange battery and a ring generator; a switch-over means for putting the line through the interface circuit or the supply circuit; two bridge resistors which are in series with the line when the latter is connected to the supply circuit and of which one is connected permanently between one of the line terminals and the output of one of the amplifiers, which output is substantially at the potential of one of the battery poles; an additional resistor, having a much higher resistive value than that of the bridge resistors and being connected between the other of the line terminals and the output of the other of the amplifiers; and a processing means within the interface circuit, which includes said detecting means and is effec

Abstract: A communications switch communicates a message to a particular access network endpoint by forwarding an identification of that endpoint along with the message, link-by-link, through the access network, the forwarding being accomplished by using previously stored routing information identifying, at the switch and at each cross-connection point, a particular downstream link over which the endpoint can ultimately be reached. The links connecting the cross-connection points am time-division-multiplexed links supporting digital loop carrier and fiber-in-the-loop communications. The routing information is generated and stored automatically by having each network element report information about itself upstream into the network.

Abstract: A subscriber apparatus having working ringer generators and a standby ringer generator which is alternately used when there is a fault, wherein provision is made of a traffic monitoring unit which continuously monitors the traffic of calls terminating at the subscriber lines and a ringer switching unit which switches a working ringer generator to a standby ringer generator when it is judged that the number of the terminating calls exceeds an allowable number, whereby the apparent capacity of the working ringer generators is increased.

Abstract: An exchange apparatus which encloses a plurality of extension terminals and connects the extension terminal designated by a signal from a line wire to the line wire, includes: a memory to store an attribute of the extension terminal; a comparator to compare an attribute designated by the signal from the line wire such as a transmission side terminal with the attribute of the extension terminal stored in the memory; and a changing circuit for changing the attribute of the extension terminal stored in the memory so as to coincide with the attribute designated by the signal from the line wire in the case where the result of the comparison by the comparator indicates that the attributes differ. Even if an attribute such as a data transmission rate or the like of the transmission side terminal differs from an attribute of the data terminal connected to the extension, communication can be started without disconnecting a call and the operating efficiency can be raised.

Abstract: A circuit for indicating the status of a telephone line at the CPE end, where the status is either on-hook, ringing, or off-hook is disclosed. The telephone line is the normal two-wire telephone line. First, a transconductance amplifier converts a floating voltage difference between the two-wire telephone line into a current. The current is proportional to the voltage difference. Next, a current to voltage converter converts the current from the transconductance amplifier to a single ended ground referenced voltage. The single ended voltage is proportional to the current from the transconductance amplifier, thus the single ended voltage is proportional to the voltage difference across the two-wire telephone line. A voltage controlled switch is turned ON when the single ended voltage is greater than a predefined value indicating the on-hook status. When the single ended voltage is below the predefined value, the voltage switch is turned OFF indicating the off-hook status.

Abstract: A bell signal generating circuit for a key telephone set. A dc component of a pulse signal is removed by a photo-coupler to generate a first signal. A high frequency component of the first signal is removed by a filter to generate a second signal. A differential amplifier amplifies the second signal to generate a bell signal. To the differential amplifier, a dc supply voltage based on the dc signal in synchronism when the pulse signal is applied.

Abstract: A ring trip detection circuit detects an OFF-hooked state of a telephone receiver during ringing of a telephone set by detecting a change in a voltage across two terminals of a transmission resistor through which a ringing signal is supplied to the telephone set from a ringing signal source.

Abstract: Device for detecting and identifying call progress tones on telephone lines. The application discloses a device for converting auditory call progress tones to visual indications and a novel circuit for identifying and distinguishing call progress tones based on their on-off cadence, if any, along with various alternative embodiments including: (1) a device which converts call progress tones to visual indications as for use by the deaf, (2) a device which is programmed to automatically go off-hook at certain times, detect a tone such as a stuttered dial tone indicating a message waiting, and activate a visual indicator, and (3) the use of a capacitor or rechargeable battery which is periodically refreshed by the device automatically going off-hook and which, while the device is on-hook, provides power required by the device.

Abstract: A call coverage arrangement where a covering terminal has, for each covered terminal, a single monitor lamp that not only indicates the overall or collective busy or idle status of the call appearances on the covered terminal but also the collective ringing status. Distinct visual signals are provided at the monitor lamp to indicate either a ringing while idle or a ringing while busy status. This allows all calls to be answered promptly and efficiently by a secretary in a manner which, from a human factors standpoint, is similar to the call coverage provided with key systems.

Abstract: A ringing signal generation circuit contains a direct current power source, a transformer, a control transistor, a rectifying and smoothing circuit, an invertor circuit, and an invertor controlling circuit. The direct current power source generates a direct current voltage. The transformer contains a primary winding and a base-driving winding in a primary side, and a secondary winding in a secondary side. The control transistor is connected in series to the primary winding and the direct current power source, and controls a current flowing in the primary winding. The rectifying and smoothing circuit rectifies and smooths a current generated in the secondary winding. The invertor circuit for converting a direct current output of the rectifying and smoothing circuit into an alternating current. The invertor controlling circuit controls the invertor circuit.

Abstract: A first part for picking up a signal being proportional to a ringing tone signal transferred on a subscriber line; a second part for extracting an ac component from the thus picked-up signal; and a third part for receiving both the signals from the first and second parts and comparing, in level, these two signals to produce a ringer stop signal if the level difference therebetween becomes larger than a setpoint value, and thus, a conventional low-pass filter can be removed.