Patents
Sitemap › H04 - Electric communication technique › H04M - Telephonic communication › H04M 3 - Automatic or semi-automatic exchanges
Patents for H04M 3 - Automatic or semi-automatic exchanges (99,881)
06/1979
06/12/1979US4158170 Line current detector
06/12/1979US4158109 Interference insensitive line supervision circuit
06/05/1979CA1056039A1 Method for through connection check in digital data systems
05/1979
05/22/1979US4156110 Data verifier
05/22/1979US4156109 Electronic traffic measuring, sorting, and recording device
05/22/1979CA1055174A1 Coin telephone station simulator and condition indicator
05/17/1979WO1979000253A1 Communication system conferencing arrangement
05/17/1979WO1979000252A1 Communication system call transfer arrangement
05/17/1979WO1979000250A1 Communication system call coverage arrangements
05/15/1979CA1054722A1 Work load regulation in a data processing system
05/08/1979US4153818 Telephone multiline signaling using common signal pair
05/08/1979US4153817 Digital conference circuit
05/08/1979CA1054277A1 Telephone circuit to eliminate use of a hold button
05/08/1979CA1054276A1 Telephone circuit to eliminate use of a hold button
05/08/1979CA1054275A1 Subscriber line testing system including exchange semiconductor cross point switching
05/08/1979CA1054258A1 Communication line test apparatus
05/01/1979US4152548 Immediate ring-back control system for time-division telephone exchange
05/01/1979US4152547 Selective monitor for an automatic telephone answering system
04/1979
04/24/1979US4151377 High impedance loop-seizing and dial pulsing circuit
04/24/1979CA1053391A1 Toll restricting method and apparatus
04/17/1979US4150260 Subscriber's circuit for four-wire-system local switch
04/17/1979US4150259 Communication system conferencing arrangement
04/17/1979US4150257 Communication system call coverage arrangements
04/17/1979US4150255 Conversational telephone call distributor
04/10/1979US4149042 Modulated RF carrier distributing arrangement for key telephone line circuits
04/10/1979US4149041 Telephone apparatus
04/03/1979US4147902 Method of automatic trunk testing
04/03/1979US4147901 Relay margin test set
03/1979
03/27/1979CA1051568A1 Videotelephone conference system
03/20/1979US4145579 Key telephone unit protective coupler
03/20/1979US4145578 Position access preference method
03/20/1979US4145577 Ringing control apparatus
03/20/1979CA1051110A1 Computer controlled automatic response system
03/13/1979CA1050638A1 Conductor identification arrangement for a cable restoration system
03/06/1979US4143250 Telephone isolation system
02/1979
02/27/1979US4142075 Interface circuit and method for telephone extension lines
02/20/1979US4140882 Methods and apparatus for special status indication in telephone systems
02/20/1979US4140880 Hold tone scanner
02/20/1979US4140879 Control circuit for transfer of auxiliary telephone equipment
02/20/1979US4140875 Four-wire, eight-leg bridge
02/20/1979CA1049170A1 Signalling device for key telephone systems
02/13/1979US4139745 Telephone line test system
02/13/1979US4139739 Telecommunications call back system
02/13/1979US4139731 Telephone conference system with active analog conference
02/13/1979CA1048669A1 Subscriber loop verification device and method
02/13/1979CA1048627A1 Multi station telephone switching system
02/06/1979US4138599 Modular communication system having self-identifying modules
01/1979
01/23/1979CA1047155A1 Connector blocks for telecommunications lines
01/09/1979US4133986 Subscriber's line equipment for a telephone exchange
01/02/1979US4132870 Key telephone system optically coupled protective coupler
01/02/1979US4132864 Digital measurement of the DC value in an AC signal adapted to telephone off-hook detection
12/1978
12/26/1978CA1045232A2 Trunk busy test circuit
12/19/1978CA1044833A1 Remote access for centrally located answering and recording equipment
12/19/1978CA1044832A1 Ring detector circuit for centrally located answering and recording equipment
12/19/1978CA1044831A1 Tape monitoring and control for centrally located automatic answering and recording equipment
12/19/1978CA1044830A1 Centrally located automatic answering and recording equipment
12/19/1978CA1044826A1 Telephone system comprising a satellite
12/19/1978CA1044790A1 Intercept arrangement for key telephone systems
12/19/1978CA1044789A1 Time-switching electronic telephony system_
12/19/1978CA1044788A1 Electronic hybrid circuit
12/19/1978CA1044787A1 Dynamic speed of answer recorder
12/12/1978CA1044389A1 Key telephone privacy circuit
12/05/1978CA1043909A1 Event monitoring transceiver
11/1978
11/21/1978US4126771 Telephone line lifting apparatus
11/21/1978US4126766 3-Port conference circuit for use in private automatic branch exchange
11/14/1978US4125748 Communication system call transfer arrangement
10/1978
10/31/1978CA1041641A1 Telephone line testing system
10/10/1978US4119807 Digital time division multiplex switching system
10/10/1978US4119806 Subscriber's line equipment for a telephone exchange
10/03/1978US4118597 Method and apparatus for detecting direct currents in a transmission line
10/03/1978CA1039816A1 Method and apparatus for positioning nuts to be welded to a base
09/1978
09/26/1978US4117278 Service observing terminal
09/26/1978US4117274 Key telephone privacy circuit
09/26/1978US4117264 Diode package for use with a central office connector module
09/26/1978CA1039391A1 Event monitoring transceiver
09/26/1978CA1039360A1 Apparatus and method to test the condition of an electric service line and to determine the presence and/or removal of electrical equipment connected to the line
09/19/1978US4115228 Method of making secondary-electron emitters
09/12/1978US4113998 Testing electrically conductive lines to determine electrical characteristics thereof
09/12/1978US4113990 Signal sending control system
09/05/1978US4112426 Apparatus for converting analog signals into digital signals and digital signals into analog signals
09/05/1978US4112258 Communication system using intelligent network processor
08/1978
08/29/1978US4110569 Method and apparatus for monitoring the on/off-hook status of a telephone set
08/29/1978CA1037625A2 Transient controlled telephone line circuit
08/22/1978US4109112 Telephone isolation device
08/22/1978US4109111 Method and apparatus for establishing conference calls in a time division multiplex pulse code modulation switching system
08/15/1978CA1036733A2 Station loop control arrangement for telephone switching system
08/15/1978CA1036732A2 Station loop control arrangement for telephone switching system
08/15/1978CA1036731A2 Station loop control arrangement for telephone switching system
08/08/1978US4105995 Digitally controlled transmission impairment measuring apparatus
08/01/1978US4104488 Subscriber line circuit
07/1978
07/25/1978US4103286 Digital binary group call circuitry arrangement
07/25/1978US4103225 System and method for determining capacitance and cable length in the presence of other circuit elements
07/25/1978US4103149 Arrangement for the performing seizure statistics for a device belonging to a group of devices
07/25/1978US4103113 Attendant console control system
07/18/1978US4101743 Test circuit for a protective coupler
07/04/1978US4099032 Loop current detector
06/1978
06/27/1978US4097694 Time-division telephone system embodying trunks having demodulating-adder circuits
06/20/1978US4096358 Key telephone system signal priority arrangement
06/20/1978US4096356 Call restriction arrangement
06/13/1978US4095058 Telephone switching system test set
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