Abstract: A telephone instrument with a 12-key keypad that has relegendable buttons. The telephone instrument is coupled to apparatus such as a personal computer, network server, or switch that is capable of performing telephony functions. The telephony apparatus responds to an input from the keypad by providing a new set of legends for the keys and/or performing a telephone function. In a preferred embodiment, the telephone instrument is connected both to a personal computer and to a POTS telephone circuit and includes a separate keypad for the POTS telephone circuit. The apparatus includes a component which detects a failure in the personal computer and automatically deactivates the keypad with the relegendable buttons, leaving the telephone instrument still available for use with the POTS circuit.

Abstract: When telecommunications systems with analog and digital circuit technology are interconnected, the two-wire/four-wire transitions are achieved with hybrid circuits in which mismatches cannot be avoided. They result in signal reflections in the form of interfering echoes which can considerably reduce speech intelligibility. The known methods of echo compensation for hands-free facilities are not suitable for compensating line echoes, since the signal level and the delay times of lines can be very different. A compander (3.7) is used to suppress the effect of line echoes, whose transmission characteristic, in addition to being controlled by a coupling factor between the transmit path and the receive path, and by a control signal determined by the noise level, is also controlled in the invention with the speech level that is received from the distant subscriber.

Abstract: An interconnect circuit is described which provides automatic three-way connection between a single base telephone line and any telephone destination, while under control of a caller from a remote location. The device may be used to make long distance calls or local calls, automatically connecting the lines to the remote caller, while telephone charges are billed to the single base telephone account. The invention device incorporates a programmable microprocessor that operates the circuit according to a program and will also accept instructions from the remote caller to program the calls in any given sequence or combination. Circuit components are operated low in stress, at low power and are few in number. Thus the circuit has high reliability and the device is low cost.

Abstract: An electronic telephone directory-dialer module which makes it possible for a user to automatically dial any party listed in the directory by using a dial tone telephone set for this purpose, without having to manually dial the telephone number code on the keyboard of this set. Included in the module is a data base and a keyboard by which one enters into the base the names, addresses and telephone number codes of all parties of interest to users of the directory. Operatively coupled to the electronic directory is a dialer constituted by a tone generator adapted to convert the telephone number code of any selected party into corresponding dial tones and to reproduce those tones in a loud speaker. The base of the telephone set is provided with a slot for receiving the module, the slot incorporating a microphone which registers with the loud speaker of the socketed module and is coupled to the telephone line.

Abstract: The present invention relates to an adaptive telephone interface for use in a telephone apparatus comprising a telephone terminal including signal amplifier means, and audio/input device. The telephone interface is disposable between the terminal and the audio/input device, and comprises a processor for generating a test signal and sending this to the terminal at a plurality of different amplitudes. The processor is further formed and arranged for monitoring signals returned from the terminal by means of sidetone coupling, so as to identify the test signal amplitude at which clipping of at least part of the test signal occurs, and consequentially adjusting the amplification by the interface of a signal received from the audio input device, before sending it on to the terminal so as to avoid substantially clipping thereof by the terminal signal amplifier means in use of the telephone apparatus.

Abstract: A two-wire line and a four-wire line telephone system interface with each other through a hybrid (12). After a connection between the two and four-wire line systems is made, an echo canceler (10) provides training signals to the hybrid on the transmit path an generates echo cancellation signals on the receive path. An adaptive filter (16) is employed to provide the proper echo cancellation signals, while a controller (22) provides filter coefficients based on an error signal. The training signals include the convolution of an impulse function with a sin(x)/x function. Once the filter coefficients are determined for the particular call, the transmit path of the four-wire line system is switched in and voice data between the two systems my commence.

Abstract: A standby feed circuit for a subscriber line comprising a constant current power feeding circuit for a subscriber line for supplying a voltage to a subscriber line at a voltage less than a standard central office power feeding circuit, a voltage source for providing the standard voltage, apparatus for applying the standard voltage when a station apparatus connected to the subscriber line is in an on-hook condition, and apparatus for applying said voltage less than the standard voltage in place of the standard voltage when the station apparatus is in an off-hook condition.

Abstract: An adjustable-period dual-tone multifrequency (DTMF) generator, which includes a plurality of programmable counters or up/down counters, a control unit, a memory unit for storing data, a digital adder, and a digital-to-analog converter. The programmable counter and the control unit are combined together to form into at least two programmable counting address generators, in which the circuit is a digit-process circuit for overcoming the problem of signal distortion that usually exists in an analog circuit.

Abstract: A Graphic User Interface, for use with electronic phonebooks, links graphic information, e.g., a graphic identifier such as a logo or picture, to a phone number that may be called using the graphic identifier. The Interface, incorporated in a telephone, enables users to send stored graphical information, tied to selected phone numbers, to other users' phones for use or storage, by scrolling through stored graphics, displayed by the Interface on the phone, to locate a graphic associated with a person or place to be called, and then, by pressing the SEND, the particular phone number or numbers linked to the selected graphic are activated and the call or calls are made. When a connection is established with a receiving number, a set of stored graphics with tied numbers may be downloaded from the memory of the sending phone to the memory of the receiving phone for similar use. The Interface can be utilized, e.g.

Abstract: A modem connected to a telephone line and capable of preventing noise from being generating upon the modem being powered-on or reset includes a ring detector for receiving a ring signal associated with an incoming telephone call through the telephone line and converting the ring signal to a binary ring signal; a datapump for processing the incoming telephone call; a controller coupled to the datapump and responsive to the ring detector, for generating an off-hook signal upon the ring signal to be detected, the off-hook signal including a leading portion of a pulse type constituting noise; a noise eliminating circuit for eliminating the leading portion of a pulse type included in the off-hook signal; and a modem driver for driving the modem in response to the off-hook signal from the noise eliminating circuit to cause a remote computer to communicate with a local computer connected to the modem or to switch a calling telephone to communicate with a called telephone.

Abstract: An improved voice activity detection system and method is provided for use in speakerphones and other voice activated systems. To facilitate switching between various operating modes, the voice activity detection scheme utilizes a new voice energy term which is based on an integral of the absolute value of a derivative of a speech signal. Voice activity is detected during a silence mode by comparing a first ratio of a current voice energy value to a background noise value with a voice activity threshold value. Voice activity is detected when the first ratio is greater than the voice activity threshold value. Another step involves identifying a direction of the voice activity during a transmit and receive mode by comparing a second ratio of a transmit path voice energy value to a receive path voice energy value with a transmit threshold value and a receive threshold value. When the second ratio is greater than the transmit threshold value, voice activity is present in the transmit path.

Abstract: A signal detection circuit includes band pass filters for detecting frequency components of a Call Alert signal (CAS) signal, a tone detection circuit for detecting whether or not a signal component is present in the output signals of the band pass filters, and two types of guard time setting circuits that have different guard times. When the CAS signal component is present, a transmitting speech signal is muted. Thereafter, with the guard time setting circuit having the normal guard time, it is determined whether or not the signal component lasts for a predetermined time period. Since the CAS signal is detected with two types of guard times, even if the transmitting speech signal contains a frequency component of the CAS signal, the transmitting speech signal is not mis-detected as the CAS signal.

Abstract: Apparatus for eliminating the necessity for manually dialing a local area code as a prefix to a call within the same area code in telephone systems in which such action is a requirement. An automatic dialer is activated and immediately transmits the local area code onto the caller's telephone line when an off-hook condition is sensed; e.g., when a telephone handset is picked up. Thus, the caller can merely then dial an ordinary seven digit telephone number within the local area code. In order to provide for the selective dialing of long distance, when the caller "flashes" his line within a predetermined period (typically, a few seconds) after picking it up, a hang-up followed by a second off-hook is emulated; however, the automatic dialer is inhibited from again transmitting the area code. Consequently, the caller is presented with a dial tone, and a telephone number, including an area code which may be different from the local area code, may be successfully dialed.

Abstract: A hands-free telephone set which is connected to both an analog cellular scheme line and a digital cellular scheme line includes first and second FIR filters. The first FIR filter is connected to a transmission path in an analog line connection state to cancel an acoustic echo generated when reception speech leaks to the transmission path. The second FIR filter is connected to a reception path in the analog line connection state, disconnected from the reception path, and cascaded to the first FIR filter in a digital line connection state. The second FIR filter constitutes a line echo canceler for canceling a line echo generated when transmission speech leaks to the reception path. In the digital line connection state, the cascaded first and second FIR filters constitute an acoustic echo canceler for canceling an acoustic echo generated when reception speech leaks to the transmission path.

Abstract: A unitary mounting carrier structure supports a display panel and acoustic transducer components within a housing sub-portion of a telephone test set containing a keypad, an earpiece receiver port, a display panel face, and an auxiliary speaker port at an end portion of the test set. The unitary carrier structure is generally wedge-configured and has a generally flat, liquid crystal display panel unit-mounting section upon which a shock-absorbing gasket assembly containing a display panel unit is mounted. An earpiece receiver-mounting section is contiguous with a wider end of the carrier, and is contiguous with the generally flat, display panel unit-mounting section. An auxiliary speaker-mounting section is supported by the carrier adjacent and transverse to the earpiece receiver-mounting section. A desiccant-retaining section is supported adjacent to the display panel unit-mounting section, and serves to reduce the dew point within the test set to a value in a range on the order of 0.degree.-65.degree. F.

Abstract: A phone holder kit comprising a box-like cradle (10, 100, 200) for accommodating a telephone set (11) and a pair of flexible headbands (12 and 14) for supporting the cradle on the user's head. Addition support is ensured by a ear mount (16) attached to the ends of headbands (12 and 14) on the side opposite to the position of the cradle. The cradle has a rubber band (30) or a padded platform (108) which supports the telephone set (11) and which can be adjusted within the cradle for adjusting the depth of location of the telephone in the cradle, depending on the dimensions of the telephone set.

Abstract: A double-talk detector for an echo canceller includes power estimators (60) and (62) which are utilized to measure the ERLE value in a calculator (64). This ERLE is stored in a register (70) when it is the largest value generated. This register (70) is updated whenever a new and better ERLE occurs. A fraction of the value in register (70) is utilized as an input to a comparator (88), and then compared to the current ERIE value. If the current ERLE differs from the SERLE in register (70) an inhibit signal is generated for blocking the updates of an adaptive filter (40). The value stored in the register (70) is periodically decremented to reduce the value thereof. This decrement operation is performed in response to detection of an utterance from the far-end. A half-Duplex operation is provided with two attentuators (352) and (354) to provide a switching operation and allow only one side access to the communication path.

Abstract: A balanced amplifier delivers a detection voltage in order to carry out power supply control. A level shift circuit shifts the level of the detection voltage to a level shift voltage for a +5 Volts system, namely, a low withstand voltage system. An adder adds a reference voltage V.sub.REF2 to the level shift voltage as a D.C bias voltage and produces an added voltage. A variable attenuator attenuates the added voltage and produces an attenuated voltage. A subtracter subtracts the reference voltage V.sub.REF2 from the attenuated voltage and produces a subtracted voltage. The subtracted voltage is converted into a current by a voltage-current converting circuit and turns back to the balanced amplifier as a signal for a high withstand voltage system. Thus, a signal process can be carried out by a circuit of a low withstand voltage.