H04M 3 - Automatic or semi-automatic exchanges

Patents for H04M 3 - Automatic or semi-automatic exchanges (99,881)
03/1980
03/11/1980	US4192975 Supply-arrangement for a line circuit
03/11/1980	CA1073569A1 Method of monitoring the on/off-hook status of a telephone set connected to a telephone network
03/04/1980	US4191859 Loop, dial pulse and ring trip detection circuit with capacitive shunt network
03/04/1980	US4191855 Full duplex audio response device
03/04/1980	CA1073136A1 Digital echo attenuator for telephone system
03/04/1980	CA1073135A1 Line circuit for key telephone systems
03/04/1980	CA1073134A1 Code-controlled detection and function actuating system
02/1980
02/26/1980	US4190744 Circuit arrangement and process for producing conference connections between three conference parties in a PCM time multiplex switching system
02/26/1980	US4189846 Process for the continuous production of solids, in particular protein concentrates, from aqueous solutions, and apparatus for the practice of the process
02/26/1980	CA1072694A1 Electronic tone ringer control circuit for telephone set
02/12/1980	US4188669 Decoder for variable-length codes
02/12/1980	US4188510 Telephone sequential number dialer with number incrementing
02/05/1980	US4187414 Circuit arrangement for an interference data alarm system in communication facilities, particularly in telephone equipment
02/05/1980	CA1071341A1 Automatic group exclusion circuit for a key telephone system
01/1980
01/29/1980	US4186283 Test set
01/29/1980	US4186282 Method and apparatus for measuring telephone line characteristics
01/22/1980	US4185189 Signal detector for monitoring electric circuits of a telecommunication system
01/22/1980	US4185174 Method and apparatus for checking connection paths in a telephone exchange
01/15/1980	US4184048 System of audioconference by telephone link up
01/15/1980	CA1070035A1 Monobus interface circuit using opto-coupled hybrids
01/15/1980	CA1070005A1 Special automatic trunk testing arrangement
01/09/1980	EP0006244A1 Telecommunication system
01/08/1980	US4182934 Method and apparatus for detecting irregular telephone calls
01/08/1980	CA1069634A1 Hold circuit for telephone
01/01/1980	CA1069232A Loop extender
12/1979
12/25/1979	US4180801 System for supervising connection points
12/25/1979	CA1068835A Voltage boost circuit for telephone systems
12/18/1979	CA1068406A1 Spoken message transmission device
12/18/1979	CA1068361A1 Initializing circuit for use in printed circuit board
12/11/1979	US4178485 Transformerless telephone line circuit
12/11/1979	US4178483 Time-division switching telephone exchange comprising a service signal sender
12/04/1979	CA1067634A1 Line circuit for key telephone systems
12/04/1979	CA1067633A1 Key telephone system interconnection apparatus
11/1979
11/27/1979	US4176402 Apparatus for simultaneously measuring a plurality of digital events employing a random number table
11/20/1979	US4175215 Multiport conference circuit
11/20/1979	CA1066793A1 Code-controlled ringer attachment for telephones
11/20/1979	CA1066792A1 Method and device for the automatic connection of tow telephone subscribers
11/20/1979	CA1066791A1 Remote accessing system for telephone lines
11/13/1979	US4174467 Ringing signal generator for use in a subscriber's line circuit
11/06/1979	US4173736 Capacitance detecting system and method for testing wire connections
10/1979
10/30/1979	CA1065455A1 Private automatic branch exchange system and apparatus
10/23/1979	CA1065072A1 Loudspeaking teleconferencing circuit
10/23/1979	CA1065071A1 Telephone station make-busy circuit
10/23/1979	CA1065037A1 Telephone switching system having automated call hold facilities
10/16/1979	US4171540 Apparatus for the control of input data into a data processor and a display device
10/16/1979	US4171469 Abbreviated dialing system
10/16/1979	CA1064632A1 Switching circuit
10/16/1979	CA1064599A1 Switching and transmission technique using a method and arrangement of channel allocation
10/16/1979	CA1064598A1 Memory operation for 3-way communications
10/09/1979	US4170740 High voltage switch and capacitive drive
10/09/1979	US4170718 Immediate ring-back control system for time-division telephone exchange
10/03/1979	EP0004497A1 Apparatus for analysing the traffic of public telephones and remote supervision installation for analysing the traffic of public telephones served by a plurality of telephone exchanges
10/02/1979	CA1063742A1 Telephone ringing control circuits
10/02/1979	CA1063741A1 Telephone ringing generators for subscriber loop carrier telephone systems
10/02/1979	CA1063704A1 Closed user group facility
09/1979
09/25/1979	US4169220 Telephone instrument connection block with remotely actuated line test
09/25/1979	US4169216 Electronic hold and hold-release circuit for a telephone set in a multiple extension single line telephone system
09/25/1979	CA1063271A1 Signal sending control system
09/19/1979	EP0004182A2 Improvements in or relating to audio teleconferencing
09/18/1979	CA1062822A1 Direct station selection hold arrangement
09/11/1979	US4167656 Junctor checking system
09/11/1979	US4167654 Telephone line feeding circuit including a protective device
09/06/1979	WO1979000648A1 Telephone system with a plurality of internal extensions and a plurality of outside lines
09/04/1979	US4166930 Transient free ring relay circuit for arbitrary time switching
09/04/1979	US4166929 Interoffice callback arrangement
09/04/1979	US4166928 Loop, dial pulse and ring trip detection circuit
08/1979
08/28/1979	US4166199 Attendant console complex
08/28/1979	US4166198 Process for operating sub-zones of a digital t.d.m. telecommunications network for long distance traffic
08/28/1979	CA1061489A1 Telephone conference amplifier
08/28/1979	CA1061440A1 Call processing restoration arrangement for telephone switching system
08/28/1979	CA1061439A1 Call denial circuit
08/23/1979	WO1979000585A1 Arrangement for measuring the ratio between a number of events occurring after each other in a first and second series of events
08/22/1979	EP0003706A1 Multipoint time division digital transmission system
08/22/1979	EP0003633A1 A method of and an apparatus for a radiotelephone communications system
08/21/1979	US4165450 Telephone signalling test system
08/21/1979	US4165447 Centralized data-registration equipment for traffic supervision in telecommunication system
08/14/1979	US4164713 Dual mode telephone subscriber loop current detector
08/14/1979	US4164632 Signalling system for overvoltage protectors
08/08/1979	EP0003433A1 Improvements in or relating to the location of contact faults on electrically conductive cables
08/07/1979	US4163871 Digital CVSD telephone conference circuit
08/07/1979	CA1060128A1 Ring trip detector with hall effect devices
07/1979
07/31/1979	US4163124 Finite storage-time queue
07/31/1979	US4163121 Radio channel control system for mobile radio telephone systems
07/24/1979	US4162376 Conference call circuit using reversible analog to digital converter
07/17/1979	US4161633 Subscriber line/trunk circuit
07/17/1979	CA1058764A1 Serial data reception system
07/17/1979	CA1058730A1 Emergency call answering system
07/10/1979	US4160878 Conference circuit with digital-analog and analog-digital conversion
07/03/1979	US4160131 Electronic key telephone system
07/03/1979	US4160127 Time-slot interchange with protection switching
07/03/1979	US4160125 Telephone polling apparatus
07/03/1979	US4160124 Multiple dial adapter
06/1979
06/26/1979	US4159402 Means for identifying subscriber lines
06/26/1979	US4159400 Toll fraud detector
06/26/1979	CA1057437A1 Subscriber's circuit for four-wire-system local switch
06/14/1979	WO1979000317A1 Digital conference circuit
06/14/1979	WO1979000316A1 Attendant console complex
06/13/1979	EP0002378A2 A control unit for establishing a four-wire link via a pair of telephone lines
06/13/1979	EP0002249A1 Circuit for time checking the duration of busy conditions in telephone exchanges
06/12/1979	US4158214 Protective device for an electronic junctor

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