Abstract: A switching system is disclosed for the concentration of a plurality of telephone lines onto a lesser plurality of intermediate trunks, wherein an independent processor is included at both ends of the concentrator system. These processors communicate with each other over a randomly chosen idle trunk, thereby negating the need for a dedicated communication link between the processors. Each processor controls the switching functions at its end of the concentrator, independently monitors and retains trunk status, subscriber line status and system operational status, and provides system fault detection, diagnosis and recovery including communication to maintenance personnel of trouble codes based on the detected fault and its diagnosis. Manual interaction with the system is also enabled at either end of the concentrator system via display and input/output units or remote from both ends.

Abstract: A transformerless two-way trunk circuit particularly useful for interconnecting a balanced lead pair and an unbalanced lead pair, with complete control over sidetone and signal level. The balanced lead pair is terminated with a first matching A.C. impedance and a second D.C. resistance means. A first transformerless circuit means applies an incoming signal from the unbalanced lead pair to the balanced lead pair, and a second transformerless circuit means applies an incoming signal from the balanced pair to the unbalanced lead pair. A third transformerless circuit means cancels signals from said first circuit means applied to the balanced lead pair to prevent them from being reapplied to the unbalanced lead pair, and a fourth transformerless circuit means cancels signals from said second circuit means applied to the unbalanced lead pair to prevent them from being reapplied to the balanced lead pair.

Abstract: A lower base support has a relatively flat portion for supporting a telephone and a raised portion with a downwardly and forwardly sloping face, shallow spring biased drawers, respectively beneath the flat portion and raised portion containing a phone number index and interchangeable note pad beneath a hinged cover on the drawer. Release keys are provided for unlatching the drawers and moving them by biasing springs to the open positions, and a central recess in the sloping face of the raised portion has a sloping support face for a calculation or tape recorder unit, with a horizontal surface portion at the top of the sloping support face to assist in pivoting the units out of the recess when inward pressure is applied to the tops thereof, similar recesses for a writing implement or a cooperating microphone, and through slots across the top of the raised portion for sound emission from an amplifier connected therebeneath in the raised portion.

Abstract: Apparatus associated with a remote communication station responds to predetermined sequences of characters received over a communication channel by initializing or conditioning equipment located at the remote station. The predetermined sequences include a plurality of synchronization characters followed by a plurality of identification characters, the latter of which identify the nature of the initialization or conditioning to occur at the remote station. The apparatus "looks" bit by bit at received data to determine when a synchronization character is received. When such a character is detected, the apparatus "looks" at the succeeding characters on a character by character basis to ascertain whether the predetermined sequence of characters is received. For each character received, a programmable read only memory produces an output which is compared with reference signals produced by another programmable read only memory.

Abstract: A circuit and a computer program for enabling the monitoring of a plurality of switch settings at remote sites by central telephone exchange equipment through regular telephone lines is described. To compensate for slow drift variations in line impedance, the impedance of each line is continually calculated from the measurements, and any small change is used to update a line impedance correction factor, while any large instantaneous change is used to update the data counter. Telephone exchange battery variations which may be large and instantaneous, are compensated for by measuring the battery voltage immediately prior to measuring the line impedances, and correcting the line impedance readings with a battery voltage correction factor. Other types of temporary signal interference which are frequently present in telephone switching equipment are identified and rejected by applying consistency criteria to multiple readings which have been corrected by the aforementioned method.

Abstract: An apparatus for use with or integrally formed of a telephone instrument, where the telephone instrument is thus functional to enable concurrent use and non-use of related equipment. The apparatus has a faceset means formed of a transmitter-receiver unit worn along a user's face for positioning the transmitter in proximity to a user's mouth and the receiver in proximity to said user's ear. A module housing the electrical circuitry controls incoming and outgoing electrical signals to the telephone instrument and transfers these signals between the faceset and the telephone instrument. Hence, the user is able to employ the faceset during a telephone conversation in a hands free manner. A mechanical linkage is formed of the module and serves to actuate the on-off switch of the telephone instrument which is placed in proximity to the module and simultaneously actuating on-off switches in the module to thereby control operation of the faceset and telephone related equipment.

Abstract: A transformerless bidirectional amplifier useful in a balanced two wire to single wire line circuit, which blocks common mode signals and allows full control of signal levels, impedances, etc. A differential amplifier circuit is connected to the balanced wires, and has its output connected through a buffer amplifier to a single unbalanced wire. A second differential amplifier has its respective input terminals connected to the input and output of the buffer amplifier. The output of the second differential amplifier is connected to one of the balanced wires, and through a resistor to one of the inputs of the first differential amplifier which is connected to the other of the two balanced wires. The value of the latter resistor is such as to apply sufficient output signal from the second differential amplifier to the first differential amplifier so as to cancel a signal from the second differential amplifier which is applied to the first differential amplifier via the first wire of the balanced pair.

Abstract: A control apparatus for an automatic radio paging system comprising a paging tone encoder circuit for generating a plurality of paging signals, a radio transmitter for transmitting the paging signals and a plurality of mobile pagers which are each tuned to a different paging signal. In particular, the control apparatus of the present invention communicatively coupled a Touch-Tone telephone subset with a radio paging system such that the person making the page is capable of initiating and controlling the paging operation from a remote telephone subset. The control apparatus provides the calling party with access to the radio paging system only after the calling party submits a properly coded access signal to the control apparatus. Thereafter, the calling party is free to initiate a page by sending paging information to the control apparatus from a Touch-Tone telephone subset.

Abstract: Circuit arrangement for time-dependent monitoring of the condition of lines with a scanning device operating with the so-called "last-look" method, which recognizes condition alterations on the line and which produces a message supplemented by the address which corresponds with the scanned line. The time-dependent evaluation is obtained by comparing an adjustable theoretical time placed in a memory with an actual time formed by a counter.

Abstract: A telephone headset including a dialing mechanism for allowing a user to place and receive calls, without being disturbed by loud noises nearby, when the headset is connected to a telephone line. The headset also includes a signaling device for alerting the user to incoming calls when a switch on the headset is in one of two given states. A dial tone is obtained prior to making outgoing calls by placing the switch in its second state.

Abstract: An abbreviated dialing system is connected in series with a telephone line connecting one or more subscriber telephone instruments to the telephone central office. This system incorporates either a low pass or other filter which prevents the transmission of Touch Tone signals from any subscriber telephone instrument to the telephone central office, but has negligible effect on the D.C. voltage, ring signal or dial tone signal sent out over the telephone line from the central office to the subscriber telephone equipment. A filter control circuit is controlled by logic circuitry to selectively either bypass the filter or insert it in series with the telephone line. When the subscriber lifts the handset of a telephone instrument, the filter is inserted in series with the telephone line. The subscriber then transmits an abbreviated series of Touch Tone signals which are intercepted and decoded by the system's logic circuitry.

Abstract: A sound wave propagated along a duct through a fluid contained in the duct is attenuated by generating sound waves from an array of sound sources spaced along the duct. Each source generates two waves travelling in opposite directions, the array being operated so that the resultant of those travelling in the same direction as the unwanted wave interferes destructively with the unwanted wave while the resultant of those travelling in the opposite direction is negligible. The array is operated in response to detection of the unwanted wave, the sound detector(s) being so positioned as to introduce a degree of acoustic coupling between the source array and the detection system.

Abstract: A speech transmission system is improved in intelligibility and naturalness by separating voiced from invoiced speech segments prior to application to a transmission channel of restricted bandwidth. Voiced segments are combined without processing with discrete-frequency coded unvoiced segments processed in analog or digital fashion conformably with the limited channel bandwidth at the transmitter. Voiced segments are reproduced conventionally while unvoiced segments are simulated by noise sources triggered by decoded discrete frequencies at the receiver. The reconstructed speech signal can thus occupy substantially more than the limited channel bandwidth.

Abstract: An electronic hold and hold-release circuit for a telephone set in a multiple extension single line telephone system has an indicator in either the tip or ring line, an electronic switch, such as a SCR, across the lines and a manually operated momentary hold button which, when operated after picking up the handset of the telephone, switches the electronic switch device to a conducting state and provides a hold current on the lines, the hold current maintained after replacing the handset. The hold condition is indicated by the indicator. An electronic device in one of the lines prevents current flow when the line voltage drops to about 10 volts, when another telephone handset is picked up, switching the electronic switch to a non-conducting state and releasing the hold. A bridge diode arrangement enables operation on either line polarity. Conveniently the indicator is an LED. Lightning and other voltage surges can be restricted by a resistor.

Abstract: Modular electronic trunk selectors are known which have a number of incoming trunk modules and a common control module. Incoming trunks are connected to outgoing trunks by the common control module. The invention disclosed is a trunk selector of this type but it includes automatic testing and fault location. Periodic tests are randomly made of incoming trunks to see if correct signals are present on certain leads between the incoming trunk module and the common control module. Checks are also made for continuity and open circuit conditions on the switching paths at appropriate times. Tests are also made when regular calls are being set up. Detection of a fault initiates a "loop-back" in the common control module to see if the fault is in the incoming trunk module or the common control module and an appropriate alarm is activated.

Abstract: An operator complex in which control signals relating to key lamp and alphanumeric display operation and key transition data are carried between the operator console and the PABX system on a multiplex highway or radio transmission link to permit virtually unlimited spacing between the operator console and the associated switching system. The operator console includes a send control system and a receive control system. The send control system detects valid key transitions and formulates a message concerning such detected key transmissions to be sent to the common control in the PABX. The receive control system receives messages from the common control indicating key lamp or alphanumeric display information and decodes these messages to effect selective control over the display.

Abstract: A circuit arrangement for combining a car radio speaker into the circuit of a car stereo system having left and right speakers; to accomplish this changeover switches, control devices for sound volume, variable resistance apparatus, damping circuits on the left and right sides, amplifiers, and illuminating members are additionally provided for carrying out the changeover between speakers as well as to control the sound quality and volume.

Abstract: A queuing technique for message communication systems having a plurality of caller handsets and multiple tariff communication links.In response to toll call requests, the lowest tariff links are scanned for availability. If no such link is available, a request is stored in a finite time, fixed storage queue, and the lowest tariff links are repeatedly scanned for availability. If no such link becomes available within a predetermined maximum time period, or if the number of requests stored in the queue exceeds a predetermined maximum number, the next lowest tariff links are scanned and the caller handset corresponding to the oldest stored request is connected to an available one of such links. If none of the next lowest tariff links are available, the oldest caller is connected to one of the regular tariff links.A second queue may be added between the next lowest tariff link group and the regular tariff link group to provide serial tandem queues or serial concatenated queues.

Abstract: A method is disclosed for automatically processing call data from a TSPS (Traffic Service Position System) over CCIS (Common Channel Interoffice Signaling) facilities to a remotely located data base system to verify the entitlement of the caller to bill the call on a credit card, collect and charge-to-a-third number basis. The call data is dialed by the caller and comprises a credit card or station number together with a PIN (Personal Identification Number) used by authorized callers in placing the special service calls. The data base system includes a memory table of authorized numbers to which the calls are charged and billed. The data base transmits CCIS direct signaling verification messages through the signal transfer system to the TSPS signifying the entitlement and nonentitlement of the caller to the call service.

Abstract: A hands-free telephone set has both transmit and receive channels open for the reception of signals, while still inhibiting feedback-singing. Two switched attenuators are provided in cascade in each channel. The first attenuator is switched after a syllable delay, and the second attenuator is switched after a yet longer delay.