Matches 1 - 42 out of 42
Match Document Document Title
7231211 Apparatus and method for monitoring a trunked radio communications system  
The present invention provides a method and apparatus for monitoring a trunked radio communications system by using some type of radio scanning receiver that is not designed for that purpose. In...
6337906 Apparatus and method for coupling an automated attendant to a telecommunications system  
An apparatus and method for coupling an automated attendant to a telecommunications system. The apparatus includes a switching device which establishes connection between a plurality of trunk lines...
6275578 Method and apparatus for providing back-up, in-band signaling in a communications network  
A method of detecting and recovering from an out-of-band signaling failure in a telecommunications network involves the reprogramming of switching centers to utilize existent inband signaling...
5263081 Method and apparatus for providing on-hook transmission for digital loop carrier channel units  
On-hook VF transmission through a channel unit to a subscriber telephone instrument is provided by a control unit which generates control signals for the channel unit. The control unit responds to...
5247574 Adaptive no balance DX signalling circuit  
The no balance duplex signalling circuit eliminates the need for setting balance resistors and capacitors to match or be proportional to cable resistance and capacitance as was required of previous...
5222129 Telephone charging signalling detector suitable for central office line interface circuits  
Detector for telephone charging signalling in the form of periodic pulses derived from alternating current signals at specific frequencies transmitted in analog form by means of a line (2)...
4907261 Universal DC signalling detector  
A DC signalling Detector (DCSD) circuit 10 for processing DC signalling information from a telephony loop. In accordance with the invention the DC signals are processed to indicate, during a first...
4852157 Multi-task state machine signalling translator  
Real-time conversion between two different A/B signal coding schemes based on the DS1 time division multiplex format is achieved by time sharing a programmable state machine. The time sharing is...
4815124 DX circuit  
An improved DX circuit may be connected to signaling and reference leads of a DX signaling link, without need to balance the internal impedance of the DX circuit against that of the external DX...
4734935 Communication system with remotely controllable signal receiving means  
A communication system having remotely controllable signal receiving means for automatically setting the receive function for a start-signal transmitted from a terminal device and for changing the...
4563547 Loop-start/ground-start line interface circuit  
A switchable common mode reference circuit for tip conductor and ring conductor line feed amplifiers provides a tip-ring common mode feedback reference for loop-start operations and a common mode...
4126765 Detector circuit for sensing battery polarity and loop closure  
A detector circuit for use in conjunction with a trunk circuit of a PABX telephone system interfacing with a central office providing for constant monitoring of normal or reverse battery...
4110565 Duplex telephone signalling system  
Disclosed is circuitry interfacing telephone branch or trunk lines to provide D.C. driving voltages in response to, for example, on-hook and off-hook signals from a telephone set. The disclosed...
4065643 Communication facility integrity checking arrangement  
Circuitry for integrity verification is provided to prevent a calling party from unknowingly remaining connected to a faulty trunk connection between an automatic switching office and an...
4058685 Interoffice loop supervision arrangement  
An arrangement for preventing false reseizures of loop-signaling, repeat coil-coupled interoffice trunk circuits for telephone switching systems is disclosed. In the prior art, false reseizures of...
4037120 Electronic dipole for looping a telephone line  
An electronic dipole circuit operating at constant current, designed to be used for looping a telephone line from a private branch exchange is disclosed. The circuit comprises a first transistor...
4002850 Trunk adapter  
A trunk adapter is associated with a common control private automatic branch exchange telephone system for interfacing the system with a central office. Four different types of adapters are...
3940570 Apparatus for combining a central telephone trunk line with a customer telephone trunk line  
A system for combining a central telephone trunk line with the trunk line of a customer exchange wherein said central telephone exchange is provided with means for separating the dial, talk, and...
3927272 Automatic circuit for providing emergency ground start signals on PBX trunks  
A circuit is disclosed for providing automatic ground start signals for a private branch exchange (PBX) telephone station equipped for automatic cut-through to a central office trunk in the event...
3919489 Thyristor circuitry for providing automatic number identification services  
Thyristor circuitry is disclosed for passing high voltage d.c. signals identifying a called non-working telephone directory number which number is automatically forwarded to an intercept operator....
3909545 Emergency transfer circuit for use in a communication switching system  
An emergency transfer circuit for permitting an operator to extend an emergency-type call via a toll switchboard trunk circuit in the event of malfunction in the switching equipment.
3894192 DX signaling circuit  
An electronic DX signaling circuit for detection of DC signals on a two-way telephone trunk circuit. A bridge network connects to a cable pair, and a voltage detection circuit connects to four...
3886315 Arrangement and method of signalling both ways through a two wire electronic junctor  
This invention relates to an electronic private automatic branch exchange which is a two wire system using junctors as a means of connecting two line circuits together via a solid state matrix. An...
3875346 Revertive pulsing  
A sending telephone central office has tip and ring conductors carrying revertive pulses transmitted thereto from a terminating central office during a revertive pulsing operation. Triggerable...
3849607 POLARITY REVERSAL SWITCHING CIRCUIT  
In a telephone type system wherein battery reversal signaling is employed, a polarity reversal switching circuit utilizing alternately enabled switch arrangements is connected between an electronic...
3761634 TOLL DIVERSION CONTROL ARRANGEMENT  
A toll diversion arrangement for private branch exchanges is disclosed in which a dial tone register circuit serves to monitor connections between restricted stations and central office trunk...
3636263 TELEPHONE SWITCHING SYSTEM  
A telephone switching office with a unique arrangement of path interconnections wherein originating junctors and incoming trunks enter one side of a route network, and terminating junctors and...
3619512 DC SIGNALING SYSTEM UTILIZING MAGNETIC AMPLIFIERS  
A pair of magnetic amplifiers have their input windings serially connected to the receiving end of a transmission line for distinguishing between four different levels of direct current transmitted...
3508008 SOLID STATE SIGNAL LEAD EXTENSION CIRCUIT FOR TELEPHONY  
3506789 AUTOMATIC GROUND START CIRCUIT FOR PRIVATE BRANCH EXCHANGES  
3410965 D. c. signalling system  
3398243 Circuit arrangement for supervising the terminal equipment belonging to a junction line extending between two telephone exchanges  
3393274 Subscriber loop and trunk loop range extension circuit  
3383470 Auxiliary line circuit  
3381094 Dial pulse incoming trunk having a self-contained pulse counter  
3310634 Supervisory signal receiving circuit  
3275750 Signal conversion circuit for "e" and "m" telephone leads  
3268667 Electronic switching telephone system  
3223786 Signaling circuit  
3218394 Ringback signaling circuit  
3043917 Telephone dial  
2943154 Toll telephone system  
Matches 1 - 42 out of 42