| Patents for H04M 9 - Arrangements for interconnection not involving centralised switching (8,105) |
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| 04/12/1994 | CA2025071C Key telephone system |
| 03/30/1994 | EP0368845B1 Controlling key-system groups from a distributed control switching system |
| 03/30/1994 | CN2160179Y Zero earth wire transmission alarm, remote measuring and voice device |
| 03/22/1994 | US5297198 Two-way voice communication methods and apparatus |
| 03/15/1994 | CA2010277C Interactive facsimile system and method of information retrieval |
| 03/02/1994 | EP0584299A1 Improved audio distribution system |
| 03/01/1994 | US5291548 Distributed telephone conference control device |
| 02/28/1994 | CA2077052A1 Incoming call manager |
| 02/22/1994 | US5289539 Echo canceller using impulse response estimating method |
| 02/01/1994 | US5283825 Telephone adaptor for telephone sets |
| 01/25/1994 | CA2048644C Method for active feedback suppression |
| 01/20/1994 | WO1994001957A1 Method for fail-safe operation in a speaker phone system |
| 01/13/1994 | DE4222465A1 Acoustic feedback susceptible electroacoustic system regulation - setting selected amplifier stage with feedback control off whenever system is put into operation. |
| 01/06/1994 | WO1994000944A1 Method and apparatus for ringer detection |
| 01/05/1994 | CN1080448A Multi-functional dispatching telephone set |
| 12/29/1993 | EP0364444B1 Internal communication system |
| 12/23/1993 | WO1993025973A1 Audio communication system for a computer network |
| 12/21/1993 | US5272695 Subband echo canceller with adjustable coefficients using a series of step sizes |
| 12/15/1993 | CN1023183C Private telephone system with simplified command feature |
| 12/14/1993 | US5271057 Audio processing system for teleconferencing system |
| 11/30/1993 | US5267306 Telephone apparatus with conditional operation |
| 11/25/1993 | DE4236046C1 Intercom system with centralised control - uses duplex amplifiers in connection path between calling and called speech stations with respective amplifier paths for each direction |
| 11/24/1993 | EP0570622A1 Circuit arrangement for telephone terminal |
| 11/16/1993 | US5263083 Method and apparatus for sharing speakerphone processor among multiple users |
| 11/16/1993 | US5263079 Dual mode cellular radio communication apparatus having an echo canceller employed in both analog and digital modes |
| 11/16/1993 | US5263019 Method and apparatus for estimating the level of acoustic feedback between a loudspeaker and microphone |
| 11/09/1993 | US5260992 Key telephone system with reduction of delay of ring tone generation at telephone set |
| 11/09/1993 | CA1324204C Communication system |
| 10/28/1993 | WO1993021034A1 Communications device |
| 10/20/1993 | EP0566194A2 Conference system with automatic speaker detection and speaker unit for use in the conference system |
| 10/20/1993 | EP0565614A1 Voice-switched handset receive amplifier |
| 10/20/1993 | EP0565526A1 Adaptive acoustic echo canceller |
| 10/19/1993 | US5255316 Hands-free telephone apparatus |
| 10/07/1993 | DE4211819A1 Hands-free telephone circuit with dynamic loudspeaker - provides loudspeaking and call tone output stages connected in parallel to loudspeaker for providing call tone signal |
| 10/05/1993 | US5251263 Adaptive noise cancellation and speech enhancement system and apparatus therefor |
| 10/05/1993 | US5251254 Control of incoming and outgoing calls in a key system |
| 10/05/1993 | US5250942 Equipment and method for management of terminal identification number in communication system |
| 09/29/1993 | CN1076821A Telephone network technology without exchanger |
| 09/23/1993 | DE4206830A1 Telecommunication installation with two sets of function keys - enables calls to be made from subsidiary installation via main switchboard to subscriber in public network |
| 09/22/1993 | EP0561133A1 Multi-channel echo cancellation with adaptive filters having selectable coefficient vectors |
| 09/21/1993 | US5247570 Telephone answering system and apparatus for direct caller selection of a party line extension |
| 09/21/1993 | US5247512 Echo canceller |
| 09/21/1993 | CA1322396C Digital key telephone system |
| 09/15/1993 | EP0560120A2 Door telephone |
| 09/02/1993 | WO1993017510A1 Feedback level estimator between loudspeaker and microphone |
| 08/24/1993 | US5239543 Communication system and a central processing unit as well as a communication station in the communication system |
| 08/17/1993 | US5237562 Echo path transition detection |
| 08/10/1993 | US5235594 Time division multiplex voice data bus |
| 07/27/1993 | US5231658 Telephone privacy device |
| 07/20/1993 | CA1320602C Voice bridge for a relay center |
| 07/20/1993 | CA1320556C Telephone system digital channel bank interface |
| 07/10/1993 | WO1993014611A1 Improved audio distribution system |
| 07/10/1993 | CA2105059A1 Audio distribution system |
| 06/29/1993 | US5224159 Key telephone system provided with telephone sets connectable to add-on modules |
| 06/24/1993 | WO1993012621A1 Intercom system |
| 06/24/1993 | DE4142007A1 Data and speech transmission system using 4-wire telephone cable - has respective line wire pairs for transmission of speech and data signal in opposite directions between speech points and exchange |
| 06/22/1993 | US5222126 Communication apparatus connected to other communication terminals |
| 06/15/1993 | US5220597 Dialing apparatus for power failure extension telephone set of key telephone system |
| 06/01/1993 | CA1318731C Electronic key telephone set with function operation test function and method of controlling the same |
| 05/26/1993 | CN1021006C Duplex centerless frequency-deivision multiple access carrier telephone system |
| 05/25/1993 | US5214691 Key telephone system with virtual private lines |
| 05/19/1993 | CN2134007Y Dispatching exchanger for mine |
| 05/18/1993 | US5212722 Hands-free telephone having a handset volume attenuator for controlling speaker volume in a hands-free adaptor |
| 05/18/1993 | CA1318003C Digital echo canceller |
| 05/11/1993 | US5210794 Apparatus and method for establishing crypto conferences on a telecommunications network |
| 04/21/1993 | EP0537370A1 Voice communication device provided with echo canceler |
| 04/21/1993 | EP0236432B1 Optical fiber bandwidth limiting method |
| 04/20/1993 | US5204861 Key telephone system with enhanced connectivity |
| 04/15/1993 | WO1993007703A1 Audio processing system for teleconferencing system |
| 04/13/1993 | US5202918 Duplex transducer for simultaneous voice broadcast and reception |
| 04/07/1993 | EP0535602A2 Programm-controlled communications system in which a connection request is simultaneously signalled at several communications terminals |
| 04/06/1993 | US5200990 Method of recovering speech path of pre-engaged call on restarting keyphone exchange system |
| 04/01/1993 | WO1993006679A1 Handsfree telephone apparatus |
| 03/31/1993 | EP0534783A2 Key telephone system with virtual private lines |
| 03/31/1993 | EP0533935A1 Telephone set |
| 03/31/1993 | CN1070526A Circuit arrangement for controlling volume range of voice terminal |
| 03/30/1993 | US5199065 Method for automatic speech direction reversal, and circuit configuration for performing the method |
| 03/30/1993 | US5199064 Fully-integrated telephone unit |
| 03/24/1993 | EP0533510A2 Cordless key telephone system with multiple tenant facility |
| 03/24/1993 | CN2128811Y Multi-purpose non-center carrier telephone |
| 03/17/1993 | EP0531796A2 Method and device for acoustic echo adaptive cancellation |
| 03/17/1993 | EP0531769A1 Circuit arrangement for dynamic control of a speech communication terminal |
| 03/17/1993 | EP0520067A4 Improved audio distribution system |
| 03/16/1993 | US5195087 Telephone system with monitor on hold feature |
| 02/16/1993 | US5187741 Enhanced acoustic calibration procedure for a voice switched speakerphone |
| 02/16/1993 | US5187705 Data error detecting apparatus for key telephone system and the detecting method therefor |
| 02/03/1993 | EP0524965A1 Private telephone system with simplified command feature. |
| 01/27/1993 | CN1068458A Multi-purpose centreless carrier telephone |
| 01/20/1993 | EP0524097A1 Device for the control of a call receiver of a telephone set in a domestic installation |
| 01/14/1993 | DE4204517A1 Microprocessor-controlled telephone circuit - uses four-wire bus for parallel subscriber devices and two-wire line for direct connection of main handset |
| 01/12/1993 | US5179588 Improved page party system |
| 12/30/1992 | EP0520067A1 Improved audio distribution system. |
| 12/30/1992 | CN1067543A Distributed automatic carrier telephone system |
| 12/15/1992 | US5172410 Conference telephone system and method |
| 12/15/1992 | US5172408 Speakerphone state-controlled alerting arrangement |
| 12/08/1992 | US5170430 Voice-switched handset receive amplifier |
| 12/08/1992 | CA1311286C Digital key telephone system |
| 12/02/1992 | EP0515966A2 Key telephone exchange |
| 11/26/1992 | WO1992021198A1 Duplex transducer for simultaneous voice broadcast and reception |
| 11/26/1992 | DE4216911A1 Verbesserung bei echowiederkehrverlusten Improvement in echo recurring losses |