Matches 251 - 300 out of 396 < 1 2 3 4 5 6 7 8 >
Match Document Document Title
5163090 Over-current verifier circuit for an enhanced subscriber line interface  
An over-current verifier circuit used in a Subscriber Line Interface Circuit (SLIC) for validating an over-current condition on a subscriber loop comprising a first counter connected to the SLIC...
5157721 Control circuit for an electrical telephone accessory  
A control circuit for an electrical telephone accessory detects if the telephone receiver is on the cradle, the telephone ringer is actuated, or if the telephone receiver is lifted from the cradle....
5155764 Telephone set with on-hook line seizure  
A telephone set is provided enabling seizure for originating and terminating calls of a telephone line connected thereto to be performed as well as release thereof, as the result both of a first...
5111502 Telephone line bridging sensor  
A telephone line bridging sensor circuit is provided which provides a variable output frequency signal to a microprocessor for measuring and storing the frequency count on a periodic basis. The...
5109409 Apparatus and method to detect telephony signaling states  
An apparatus and method for detecting telephony signaling states, comprises an analog to digital converter and a microcomputer with associated firmware for controlling the operation of the...
5083308 Arrangement for determining switch port status at an adjunct processor  
An arrangement that enables an adjunct processor to determine the service status of switching system communication ports to which the adjunct processor is connected, without reliance on...
5070526 Signal analyzing system  
An analog communication signal such as the signal transmitted over a telephone line is converted to digital form for storage in the memory of a computer. Segments of the digital representation of...
5063593 Tone-type recognition method  
There is disclosed a tone type recognition method capable of recognizing a call progress state of a central office line switching system by using a tone detector. The method enables the system to...
5038372 Systems for transmitting data via telephone lines  
A system for transmitting data via a telephone line by means of a data communications device (4) connected to the telephone line, at least one other communications device being connected to the...
5020100 Telephone line loop current regulator  
A telephone line loop current regulator combines the functions of current regulation, current detection, loop disconnect signalling and speech switching. It comprises a gyrator circuit formed by...
4998271 Telephone accessory  
An apparatus for use with a telephone including, in one embodiment, a detector for detecting when the telephone is in an off-hook condition and disconnect circuit for eliminating the off-hook...
4980911 Transient signal elimination circuit for telecommunications applications with CPU control means  
Transient signal elimination circuitry is disposed in a local communications loop extending from a subscriber telephone to a telephone central office couples ringing and on-hook and off-hook...
4958371 Method and apparatus for determining when a telephone handset is off-hook  
Apparatus in an automatic telecommunications system which communicates between a central location and at least one remote location over the switched telephone network, senses changes in loading of...
4953200 Private branch exchange capable of discriminating different types of telephone sets connected thereto  
A private branch exchange for use with different types of telephone sets comprises a current detection device such as a photo-coupler for detecting a current flowing through a data line connecting...
4944001 Rotary dial pulse receiver  
Apparatus and method for receiving and decoding the bursts of line current activity produced by rotary dial action in dialing a sequence of digits. In accordance with the apparatus of the present...
4935959 Two-wire telecommunications line detection arrangements  
A loop closure detector for a two-wire telephone line comprises a four-arm resistive bridge, in which the four arms are constituted respectively by a first battery feed resistor, the two-wire line...
4935958 Busy/no-answer call completion equipment  
Apparatus for recognizing a telephone call supervision signal by comparing its frequency and cadence to the frequency and cadence of a previously learned call supervision signal is provided as part...
4922529 Automatic hangup apparatus for restoring service to off-hook telephones  
The hangup apparatus uses an inadvertent off-hook detector circuit designed to detect the off-hook "howler" alert signal transmitted to a telephone by the telephone company when the telephone has...
4899379 Circuit arrangement for the connection of line circuits of a digital time multiplex-telephone network  
A circuit for implementing a connection of an operational amplifier, and for achieving the switchable sensitivity of the same, as well as the in-and-out switchable filter elements, which results in...
4897871 Apparatus for transmitting and/or receiving balanced signals on a two-wire telecommunication line  
A transformerless hybrid circuit arrangement for a subscriber line interface circuit of a telecommunications exchange is disclosed. A preferred embodiment of the hybrid arrangement comprises a...
4868873 Pulse detector for counting dial generated pulses  
A pulse detector system for reliably counting pulse signals generated by calling party telephone dials. The system includes generating a dial pulse template based on a sample train of pulses. A...
4864605 Telephone trunk interface circuit  
A solid-state telephone trunk interface circuit provides high isolation between a central office and telephone equipment. Opto-isolator transistors and a transformer are used to isolate the central...
4864606 Terminal apparatus with a handset using a four pin connector  
A communication terminal apparatus having a handset which includes a transmitter, a receiver and a hook switch. The handset is connected to the main body through a modular jack having four pins....
4862495 Telecommunications subscriber line interface circuit and party identification facility  
The invention provides a tip party identification facility in association with a subscriber line interface circuit. The tip party identification facility takes advantage of a shutdown feature and...
4847896 Monolithically integratable telephone circuit for supplying ringing signals to a subscriber's telephone line and for detecting an off the hook condition during ringing  
A telephone circuit, which may be monolithically integrated, for supplying ringing signals to a subscriber's telephone line and for detecting an off the hook condition during ringing, including a...
4839920 Method for determining telephone dial pulse parameters independently of subscriber line length  
A method is disclosed for measuring telephone dial pulse parameters independent of telephone subscriber line length. To avoid distortions resulting from varying subscriber line lengths, there is...
4827505 Subscriber line interface circuit  
A subscriber line interface circuit receives and twice inverts currents from a 2-wire subscriber line and returns the currents to the subscriber line so longitudinal input impedance is low. Any...
4817137 Apparatus for remotely determining hook status conditions  
An apparatus for effectively monitoring the hook status of a remotely stationed telephone, and a sub-audible tone associated with a corresponding alarm reporting device, monitors variations in...
4811389 Parallel off hook detector for electronic remote data recorder  
A parallel off hook detector for an electronic remote data recorder includes a short-integrator and a long-term integrator, both monitoring the voltage on a line. The integrated outputs of the...
4805213 Ring detector  
A device for detecting a specified signal on a conventional telephone line includes a pair of input terminals to which to connect a pair of conventional telephone lines, and a circuit connected to...
4803718 Hold detecting and control circuit for a key telephone system  
A key telephone system for use with at least two telephone lines that extend between a central office and two or more telephone stations. Each station is capable of responding to a...
4802207 Voltage-sensitive telephone line monitor  
Detector circuitry monitors the line voltage on a telephone line to detect an off-hook condition. In order to accomodate varying line voltages and noise conditions, the circuitry automatically...
4766605 Telephone tie trunk driver circuit  
A driver circuit to drive an M-lead in a tie trunk between telephone branch exchanges is disclosed. The driver continues to provide for a current increase as the resistance of the load on the...
4742539 Telephone loop current modulator  
An improvement to automatic answering and call forwarding features used in telephone communications which allows a user to remotely activate, modify, and deactivate these features. The improvement...
4742536 Telephone monitor circuit and method  
A communication system is connected to a pair of telephone conductors which supply telephone service to a telephone subscriber. An optically coupled switch connects a first winding of a transformer...
4736412 Method of and circuit arrangement for evaluating the output signals of current flow detectors in telecommunication facilities  
The flow of direct current and/or ringing alternating current in a telephone line subscriber loop is detected by means of current flow detectors. The output signals produced by the current flow...
4734933 Telephone line status circuit  
A circuit for detecting a first plurality of status signals on a multiplicity of telephone lines and generating a second lesser plurality of control signals, less than the first plurality, in...
4731829 Circuit for detecting current variations  
The circuit of the present invention detects variations of a current I L flowing in a telephone line LL. A low-value resistor r is connected in series with line LL. A constant voltage generator is...
4731827 Interswitch line circuit  
A tip-ring interface that utilizes a single detector to detect ringing, forward loop current, and reverse loop current. In one embodiment, forward or reverse battery state may be detected when...
4686700 Telephone off-hook detector circuit  
A circuit for connection into a telephone line for detecting when a telephone instrument has gone off-hook and which is unaffected by the presence of a ringing signal on the telephone line. The...
4677662 Multiple line self-contained telephone  
A detection circuit is provided for indicating whether a telephone line is in use or is available or is on hold. The simplified circuit can be incorporated within a telephone instrument so that no...
4674117 Subscriber line circuit having an improved offhook supervision circuit  
An improved offhook supervision circuit including an amplifier connected to a subscriber loop through the tip and ring conductors of a subscriber line circuit. The amplifier is arranged to develop...
4639553 Call signal detecting device  
In a facsimile communication system, a call signal detecting device for identifying call signals which are received over a network. Both an unsounding call signal and a sounding call signal are...
4636587 Electronic switch for digital telephone  
An electronic switch for supplying power to a digital telephone which consumes substantially no power in the idle mode. A transistor for supplying power to the digital telephone is latched on in...
4634814 Surge protected electronic switch for telephone voiceband circuits  
A fast response electronic switch used for control of connect and disconnect functions, primarily related to speech network applications for electronic-microprocessor based telephones utilizing...
4623760 Signaling protocol interface channel unit  
Disclosed is a channel unit for directly interconnecting a toll office multiplex line and a terminal unit line such as that of a private branch exchange (PBX) or a telephone station set, thereby...
4614843 Arrangement for opening the loop for a well-defined time interval from a telephone set  
Telephone set with key for opening the loop for a predetermined time interval. A monostable triggering circuit includes an MOS transistor connected in series with the transmitter and dialing...
4609783 Automatic telephone answering apparatus  
In an automatic telephone answering apparatus, a ringing tone generated upon reception of an incoming call is detected by a ringing tone detecting means, a pulse or leakage flux generated upon...
4602130 Dual voltage source feed circuit configuration for a telephone line circuit  
A dual voltage source feed circuit arrangement for a two-wire telephone line circuit includes an auxiliary voltage source placed across the two-wire line and switchably controlled to connect the...
4593156 Grounded tip detector  
A grounded tip detector for use in a subscriber line circuit detects and indicates a tip-to-ground condition in the SLIC. Hysteresis and RC filtering are provided to assure a sharp switch-over of...
Matches 251 - 300 out of 396 < 1 2 3 4 5 6 7 8 >