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)
07/1981
07/28/1981US4281219 Telephone line circuit
07/23/1981WO1981002082A1 Method of automatic switching in a communication network and switching centre therefor
07/22/1981EP0032410A1 Telephonic betting system for lotto or other authorized games of chance
07/21/1981US4280021 Message waiting system
07/14/1981US4278931 Location of contact faults on electrically conductive cables
07/14/1981US4278849 Test arrangement for automatic number identification systems
07/14/1981US4278844 Communication system selective call screening arrangement
07/14/1981US4278843 Two-way amplifier arrangement
07/14/1981CA1105162A1 Telephone line circuit
07/09/1981WO1981001901A1 Automated conversation system
07/07/1981US4277655 Automatic gain repeater
07/07/1981US4277649 Method and apparatus for screening telephone calls
07/07/1981CA1104698A1 Automatic telephone exchange system capable of communication of speech signals and data transfer
07/01/1981EP0031014A1 Telecommunication system
06/1981
06/30/1981US4276639 Telephone exchange with time shared speech paths and selectively attenuated speech signals
06/30/1981US4276451 Control system for telephone switching system
06/30/1981US4276447 Signal processing apparatus for subscriber circuits
06/24/1981EP0030724A2 Method and device for carrying out objective measurements on digital speech transmission systems
06/24/1981EP0030708A1 Switching system with paging function
06/23/1981US4275268 Mixing apparatus
06/16/1981US4274155 Multiport conference circuit with multi-frame summing and voice level coding
06/10/1981EP0029938A1 System for electronic audio communication
06/09/1981US4272810 Arrangement for deleting trailing message portions
06/03/1981EP0029627A1 Device for detecting the looping of a subscriber line during ringing
06/02/1981US4271502 Digital voice conferencer
06/02/1981CA1102422A1 Arrangement for supervision of the seizure condition quality for a device belonging to a group of devices
05/1981
05/27/1981EP0029246A1 System for the broadcast of information by means of the telephone network
05/26/1981US4270030 Testing of subscriber loop pair gain systems
05/26/1981US4270024 Telephone line activity monitor
05/26/1981CA1102025A1 Methods and apparatus for special status indication in telephone systems
05/20/1981EP0028688A1 Lay-out for transmitting control signals via a speech channel
05/19/1981US4268716 Audio teleconferencing
05/19/1981US4267646 Telephone question and answer training device
05/19/1981CA1101529A1 Multiport conference circuit
05/19/1981CA1101528A1 3-port conference circuit for use in private automatic branch exchange
05/13/1981EP0028416A1 Broadband switching system
05/13/1981EP0028415A1 Broadband coupling arrangement
05/12/1981US4267593 Method and means for digital conferencing
05/05/1981US4266097 Device control system
04/1981
04/22/1981EP0027226A1 Testing system for a connection network
04/21/1981US4263482 Public telephone station traffic analyzing arrangement
04/16/1981WO1981001090A1 Telephone loop resistance detector
04/15/1981EP0027042A2 A network connection system
04/08/1981EP0026413A1 Circuit arrangement for registering the switching state in a circuit especially constituted by subscriber lines in telephone exchanges
04/08/1981EP0026412A1 Circuit arrangement to avoid the adverse effect of the share of alternating tension during the registration of the switching state in a circuit especially constituted by subscriber lines in telephone exchanges
04/08/1981EP0026411A1 Circuit arrangement for determining the switching state of a subscriber line in telephone exchanges
04/08/1981EP0026187A1 Communication system tracking arrangement.
04/07/1981US4260859 Method and apparatus for detecting transmission system failures in a communications network
04/01/1981EP0026165A1 Private automatic branch exchange (PABX) with interception facility
04/01/1981EP0026020A1 Telephone set
03/1981
03/31/1981US4259549 Dialed number to function translator for telecommunications switching system control complex
03/31/1981CA1098631A1 Ringing signal generator for use in a subscriber's connecting circuit
03/25/1981EP0025454A1 Telephone-conferencing apparatus and method
03/24/1981US4258236 Remote telephone line switching and testing
03/24/1981US4258232 Line hold circuits
03/24/1981CA1098226A1 Ringing and testing control circuitry for communication systems
03/17/1981US4257120 Multiport conference circuit with multi-frame summing
03/17/1981US4256928 Telephone call diverting and answering system
03/17/1981US4256926 Microprocessor control complex for a telecommunication switching system
03/10/1981US4255625 Call processing monitor system
03/10/1981US4255624 Call processing monitor system
03/10/1981US4255623 Apparatus for pulse train measurement
03/10/1981US4255619 Telephone reservation-processing system
03/10/1981US4255618 Digital intercept recorder/announcer system
03/03/1981US4254497 Multiport conference circuit with voice level coding
03/03/1981US4254305 Current limited subscriber line feed circuit
03/03/1981CA1096981A1 Interference insensitive line supervision circuit
02/1981
02/24/1981US4253000 Method and system for reducing conference bridge oscillations
02/24/1981US4252998 Identifier for manual switchboards with conference facility
02/24/1981CA1096522A1 Subscriber line-trunk circuit
02/17/1981US4251692 Telephone call restricting apparatus
02/11/1981EP0023689A1 Logic apparatus for the preprocessing of alarm signals
02/10/1981US4250354 Telephone day count traffic observing and data accumulating equipment
02/10/1981CA1095430A1 Programmed conversation recording system
02/03/1981CA1095192A1 Digital type telephone system having a conference function
01/1981
01/30/1981EP0022786A4 A traffic measuring device based on state transitions.
01/28/1981EP0022786A1 A traffic measuring device based on state transitions
01/27/1981US4247910 Arrangement for deleting leading message portions
01/27/1981US4247742 Trunk test circuit
01/27/1981CA1094705A2 Telephone apparatus
01/20/1981CA1094209A1 System for monitoring the operational ability of data processing equipment
01/13/1981CA1093719A1 System of audioconference by telephone link up
01/13/1981CA1093663A1 Junctor checking system
01/07/1981EP0021710A1 Method and means for digital conferencing
01/07/1981EP0021309A1 Circuit arrangement for telecommunications exchanges, in particular telephone exchanges, with the metering impulse frequencies graduated according to time
01/07/1981EP0020822A1 Current detector circuit
01/06/1981US4244046 Digital data transmission system providing multipoint communications
01/06/1981US4243844 Hold circuit for telephone system
01/06/1981CA1093230A1 Message-waiting and do-not-disturb communications system
01/06/1981CA1093194A1 Communication system conferencing arrangement
12/1980
12/30/1980US4242539 Telephone information displaying device
12/30/1980CA1092734A2 Recursive-like adaptive echo canceller
12/30/1980CA1092653A1 Method and apparatus for measuring telephone line
12/16/1980CA1091833A2 Recursive-like adaptive echo canceller
12/09/1980US4238851 Packet transmission system
12/09/1980US4238649 Call simulator
12/09/1980CA1091373A1 Signalling system for overvoltage protectors
12/09/1980CA1091335A1 Communication system call transfer arrangement
12/02/1980US4237339 Audio teleconferencing
12/02/1980CA1090928A1 Dual mode telephone subscriber loop current detector
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