Abstract: An electronic device for providing information related to an input telephone number includes a keyboard unit for providing an input telephone number and a memory unit for storing an IDDD code and a database including country code entries, country name entries which correspond to the country code entries, area code entries, area name entries which correspond to the country code entries, and information related to each of the country name and the area name entries. A central processing unit receives the input telephone number from the keyboard unit and compares the received input telephone number with the contents of the memory unit. The central processing unit then controls a display unit to show the input telephone number, the country name entry and the area name entry corresponding to the input telephone number, and the information related to the country name entry and the area name entry corresponding to the input telephone number.

Abstract: A liquid crystal display driver and power supply for use with a telephone dialing circuit reduces the potential of an external power supply to the telephone dialing circuit to a desired voltage level. The reduced potential is then stabilized and a second voltage signal, which is a function of the stabilized voltage signal, is generated to drive and supply power to a liquid crystal display of the telephone dialing circuit. The liquid crystal display driver and power supply and the telephone dialing circuit can be integrated in a single IC chip.

Abstract: A multi-frequency signal receiver, and in particular a push-button signal receiver, is provided having a detector circuit and an amplitude variation supervisory circuit. The detector circuit has a group of band pass filters, each having a pass band corresponding to each elemental signal in the multi-frequency signal. The detector circuit also has a logic circuit for receiving each output from the band pass filters and outputting detected data of the multi-frequency signal. The amplitude variation supervisory circuit monitors the amplitude of an input signal for a predetermined duration and detects and holds the maximum value of the monitored amplitude. Then, the amplitude variation supervisory circuit detects when the amplitude of the input signal exceeds the maximum amplitude value to determine if the input signal is not the multi-frequency signal.

Abstract: A portable telephone system is disclosed in which a plurality of i-th class exchanges, which accommodate key service units of a plurality of portable telephone sets present in each service area, and at least one (i+1)th class exchange which accommodates the plurality of i-th class exchanges through junction lines, are stratified to form an exchange system so that i=1, 2, 3, . . . , and so that the (i.1)th class exchange covers all service areas. The exchange system has a function whereby information which specifies the home area of each portable telephone set and the portable telephone set in distinction from each other is registered in the i-th class exchange and the (i+1)th class exchange, which administer the home area.

Abstract: A device for setting and tone dialing a single telephone number includes a telephone number setting device to generate a digital signal corresponding to the binary equivalent of the digits of the telephone number to be set. A tone generator receives the digital signal generated and groups the digital signal into a predetermined number of bit groups. Each of the bit groups corresponds to one of the digits of the telephone number. The bit groups are accessed one at a time and a dual tone multi-frequency signal corresponding to the digit represented by the accessed bit group is generated by the tone generator and is directed to the telephone instrument.

Abstract: A telephone headset on-line indicator uses a light emitting diode located on a boom of a headset to indicate that the user is on-line with another telephone. Circuits are described for use with use with conventional telephones, electronic telephones and PBX telephone base units.

Abstract: A sound generation circuit for producing a dual tone which includes memory circuitry for storing data for controlling production of the dual tone, selection circuitry for selecting data stored in the memory circuitry and frequency dividers for producing an output signal having a frequency which varies based on the data selected by the selection circuitry. The production of the dual tone is based on the output signal of the frequency dividing circuitry. The sound generation circuit also includes logic circuitry to inhibit selection by the selection circuitry of data for controlling production by the sound generation circuit of a musical note when the sound generation circuit is currently producing a dual tone. The melody and dial sections of the sound generation circuit employ common elements.

Abstract: In an apparatus for driving a service function unit of a multi-function telephone set, each service function is carried out by pushing one hardware type programmable key. The pushing of the programmable key is to read programmed service information stored in a memory, and to process the read service information, so that the service function is easily carried out by a single key operation by a user of the telephone set.

Abstract: A metallic channel unit network for interconnecting a two-wire, bidirectional signal transmitting means and a four-wire signal transmitting means in a communication system includes a voice hybrid driver, A/D signal processing circuit, D/A signal processing circuit, tip and ring switching drivers, and tip and ring sensing amplifiers. The metallic channel unit network is suitable for use with substantially all of the different alarm-signalling techniques utilized by the various alarm companies for connecting their equipment to a channel bank multiplexer coupled to the four-wire means. The metallic channel unit network provides an apparent metallic cable pair over the digital carrier in the frequency range of DC to 3.5 KHz with an amplitude variation between +200 to -200 VDC.

Abstract: A method for automatic speech direction reversal includes supplying a reception signal with variable damping to a loudspeaker, outputting a microphone signal with variable damping from a microphone as a transmission signal; continuously classifying each of the reception signal and the microphone signal as a speech signal or noise; setting the damping of one of the signals classified as the speech signal to a first damping value, setting the damping of the other of the signals to a second damping value being higher than the first damping value, and maintaining the set damping until the one signal is classified as noise. The preceding damping values are maintained if both of the signals are classified as a speech signal. Both damping vlaues are set to a third damping value being located between the first and second damping values if both of the signals are classified as noise.

Abstract: Double talk is rapidly detected for effectively preventing degradation of echo cancellation in a long distance telephone communications system. An echo estimator includes a transversal filter and receives an incoming signal and tap coefficients, and then adaptively produces an estimated echo signal. A subtractor is adapted to subtract the estimated echo signal from an echo signal applied thereto, and outputting an error signal indicating residual echo. A tap coefficient updating circuit is coupled to receive the error signal and the incoming signal and the tap coefficients, and renews the tap coefficients. A double talk detector is coupled to receive the error signal and the incoming signal and the echo signal. The double talk detector issues a double talk detection signal in the event that a cross-correlation value between the incoming and echo signals is less than a first predetermined level while an estimated echo cancellation is larger than a second predetermined level.

Abstract: Data communication apparatus which dials based on the preregistered telephone numbers, prohibits or allow data communication based on the telephone number data the apparatus includes a memory to memorize the data for judging if data communication is allowed for a telephone number an a control to control dialing based on the result of such judgment.

Abstract: A line interface circuit supplies energizing direct current from a power source via tip and ring leads of a two wire communications line connected with a telephone apparatus, and also couples alternating current signals between the telephone line and an associated telephone facility. The line interface circuit is provided with tip and ring terminals for connection to the tip and ring leads, and power terminals for connection to the power source. Coupling circuitry is connected in series with the tip and ring terminals for providing paths for the energizing direct current and for the alternating current signals. An active tip feed circuit is connected in series between the tip terminal and the coupling circuitry for providing a tip feed path having a predetermined resistance while the telephone apparatus is in an OFF HOOK state and having a much higher resistance in response to an excess of voltage at the tip terminal.

Abstract: An acoustic calibration circuit in a voice switched adaptive speakerphone accurately determines the type of acoustic environment of both large and small rooms having either harsh or favorable acoustics. The calibration circuit determines the acoustic environment of a room by emitting a tone burst through a loudspeaker associated with the speakerphone and generating an echo decay parameter that is indicative of the duration of echoes from the tone burst signal measured with a microphone also associated with the speakerphone. The echo decay parameter is generated from a composite representation of the acoustic response for those echoes having the largest returned amplitude level measued at each one of multiple predetermined time intervals by the calibration circuit.

Abstract: A dial number generator includes a plurality of cards (C1, C2, C3) having a display section on which a large number of subscribers are symbolically displayed and a identification section for (10, 10a) for identifying the type of the card. The generator further includes a main body (1), in which the plurality of cards are housed in a cavity (9) which generates a dial signal in facsimile transmision, etc. The main body has a transparent touch panel (5) by which the symbolic display of one card which is housed can be selectively pressed from the outside of the main body, a detection device (200) capable of identifying the type of the one card, and a device (221) for generating a dial number of subscriber to be called corresponding to a signal output from both the transparent touch panel and the detection device.

Abstract: An enhanced high voltage line interface circuit for a digital switching system over which a connection is established between a digital switching system and a subscriber instrument via a subscriber loop. The high voltage line interface circuit includes in combination circuits that provide power to the subscriber loop and convert received analog voice signals transmitted from the subscriber instrument into differential voltage voice signals for subsequent conversion to digital data for use by the digital switching system. Additionally, differential voltage voice signals from the digital switching system are converted to analog voice signals for transmission along the subscriber loop to the subscriber instrument. The high voltage line interface circuit further includes circuits that detect and monitor the subscriber loop status and develop digital logic output signals that are used to report the status of the loop to a digital switching system controller.

Abstract: A communication system has a two-wire communications path carrying analog transmission and reception signals, and a four-wire communications path including a two-wire transmission path carrying digital transmission signals and a two-wire reception path carrying digital reception signals. A two-wire/four-wire converter for coupling the two-wire communications path to the four-wire communications path includes an analog/digital converter having an input coupled to the two-wire communications path and an output. A digital filter has an adjustable communications function for generating a predetermined terminating impedance for the two-wire transmission path. The digital filter has an input connected to the output of the analog/digital converter and an output connected to the two-wire reception path. An adder has one input connected to the two-wire reception path, another input connected to the two-wire transmission path and an output.

Abstract: A speaker telephone comprising a microphone outputting an electrical signal, and a loudspeaker is disclosed. An amplifier has its output coupled to the loudspeaker. This amplifier has non-inverting and inverting inputs. A switch having two positions couples the microphone to the amplifier or couples the tuning signal source to one of the inputs of the amplifier. A tuning signal source and control circuit output a tuning signal. Initiation means initiates a tuning sequence by causing the switch to be in the second position and causing the tuning signal source and control circuit to generate tuning signals. A coupling device is connected to one of the inputs of the amplifier and adopted to be connected to a telephone circuit. A hybrid voltage generator circuit is responsive to the output of the microphone when the switch couples the microphone to the amplifier to generate at its output a cancellation signal which prevents transmitted voice signals from appearing at the loudspeaker.

Abstract: Apparatus for detecting and identifying DTMF signals in connection with a voice store and forward equipment (VSF) and for preventing talk-off, whether generated by the VSF or by a user of the VSF.

Abstract: A telephone line card circuit includes an operational amplifier circuit having first and second inputs and an output. A field-effect transistor circuit has first, second and control electrodes, the control electrode is coupled to the output of the operational amplifier circuit, the first electrode is coupled to the TIP/RING terminal, and the second electrode is coupled to the second input of the operational amplifier circuit. A first resistor is coupled between the TIP/RING terminal and the first input of the operational amplifier circuit. A second resistor is coupled between the first input of the operational amplifier circuit and a terminal of the circuit whereby the terminal of the circuit is typically coupled to a supply voltage terminal.