Patents
Sitemap › H04 - Electric communication technique › H04M - Telephonic communication › H04M 9 - Arrangements for interconnection not involving centralised switching
Patents for H04M 9 - Arrangements for interconnection not involving centralised switching (8,105)
12/1989
12/12/1989US4887288 Self calibration arrangement for a voice switched speakerphone
12/05/1989US4885773 Apparatus for mounting a unidirectional microphone in a hands-free telephone subset
12/05/1989US4885569 Method and device for transferring signals between modules of an electronic unit
11/1989
11/22/1989CN2048268U Bus-type master-slave intercom
11/16/1989WO1989011186A1 Intercom telephone
11/09/1989DE3814015A1 Method for digital transmission of information for communication switching systems
11/08/1989EP0340516A1 Speakerphone using digitally compressed audio to detect acoustic feedback
11/08/1989EP0340231A1 Communications systems
11/07/1989US4879745 Half-duplex speakerphone
11/07/1989CA1262755A1 Radio telephone system control apparatus and method
11/02/1989EP0339432A2 Method for a calculator-controlled switching device, especially for a key-telephone exchange, in which data and telephone terminals are connectible alternatively
11/01/1989CN2047084U Multichannel subscriber telephone bridging device controlled by micro-computer
10/1989
10/18/1989EP0337619A1 Communication system
10/18/1989CN1036489A Time-sharing pulse-amplitude modulating full-automatic bloc telephone
10/10/1989US4873718 Feature telephone integration device
10/05/1989WO1989009518A1 Communication system
10/04/1989CN2045558U Trunk type calling and speaking apparatus between principal and subordinate
09/1989
09/26/1989CA1261494A1 Apparatus for selectively alerting party line subscribers
09/20/1989EP0333581A1 Echo cancelling device with filtration into frequency sub-bands
09/20/1989EP0333051A2 Free programmable exchange device for a loudspeaker intercom exchange
09/20/1989CN2044781U Multipurpose machine for electronic safeguarding building
09/19/1989US4868847 Telephone intercom device
09/19/1989CA1259718A1 Optical local area network using a common optical carrier with separate user angle modulation
09/14/1989DE3807358A1 Method for controlling an intercom system
09/14/1989DE3807149A1 Method for identifying the occurrence of the same subscriber device address for a subscriber device in a ring-shaped communications network
09/14/1989DE3807148A1 Method for identifying the occurrence of the same subscriber device address for a subscriber device during the formation of an address table in a ring-shaped communications network
09/13/1989EP0331838A2 Digital key telephone system
08/1989
08/31/1989DE3805357A1 Circuit arrangement for dynamic range control of speech signals
08/30/1989EP0330384A2 Hands-free telephone
08/08/1989US4856058 Office line interface circuits
08/08/1989US4855995 Method and system for data transmission
08/01/1989CA1258112A1 Computer controlled multi-link communication system
07/1989
07/27/1989DE3829051A1 Terminal identification control circuit
07/26/1989EP0205563B1 System for selectively coupling a plurality of data stations into a single communications path
07/26/1989CN2041873U Wired-wireless interface
07/25/1989US4851811 Communication device for entries of buildings
07/19/1989EP0324058A1 Key telephone system
07/18/1989US4850012 Automated access facilities for use with key telephone systems
07/18/1989US4850011 Key telephone system providing selection of key or PBX operational modes
07/18/1989CA1257650A1 Optical fiber bandwidth limiting method
07/13/1989WO1989006463A1 Multi-use telephone extension control circuit and device
07/11/1989US4847897 Adaptive expander for telephones
07/11/1989US4847888 Field telephone system
07/04/1989US4845497 Conference circuit for a digital communication system
07/04/1989CA1257020A1 Method, station and system for the transmission of messages in the form of packets
06/1989
06/29/1989WO1989006076A1 Automated access facilities for use with key telephone systems
06/27/1989US4843621 Speakerphone using digitally compressed audio to detect acoustic feedback
06/20/1989CA1256036A1 Microphone actuation control system suitable for teleconference systems
06/15/1989DE3740652A1 Device for improving the side tone suppression or loop gain in intercom systems
06/14/1989CN2039482U Multichannel doorbell telephone
06/13/1989CA1255826A1 Building intercom system
06/07/1989EP0319139A2 Digital key telephone system
06/06/1989US4837807 Station to station message arrangement
06/01/1989WO1989005068A1 Process for adaptive compensation of echoes in a communication system
05/1989
05/31/1989EP0203147B1 Automatic redialing arrangement for multi-line telephone station sets
05/30/1989US4835484 Gain control circuit for suppressing Larsen effect in a loudspeaker telephone
05/18/1989WO1989004573A1 Call appearance reservation arrangement
05/16/1989US4831651 Intermediate amplifier for use in two-wire connections of a dial telephone network and method for the gain control of said amplifier
05/16/1989US4831516 Data transmission system between a main CPU board having a wait signal generating latch and a plurality of CPU boards
05/09/1989US4829565 Telephone with background volume control
05/09/1989US4829513 Time slot summation communication system for allowing conference calls
05/09/1989CA1253939A1 Graphics based call management
05/03/1989CN2037126U Telephone call device
05/02/1989US4827461 Universal telecommunications audio coupling device
04/1989
04/19/1989EP0311808A2 Method and circuit for noise compensation in microphones
04/18/1989US4823377 System for setting registration mode for key telephone set
04/18/1989CA1252866A1 Communication system having voice and data capability
04/11/1989US4821319 Single line telephone communication system
04/11/1989US4821316 Key telephone system
04/06/1989WO1989003139A1 Method for terminating a telephone call by voice command
04/04/1989US4819263 Apparatus and method for hands free telephonic communication
03/1989
03/28/1989US4817132 Controlling the connection of a predetermined number
03/21/1989CA1251587A1 Ringing signal reformatting circuit
03/21/1989CA1251585A1 Interphone system with security function
03/16/1989DE3822353A1 Hands-free system
03/08/1989CN1003555B Full duplex speakerphone for radio and landline telephones
03/07/1989US4811390 Control circuit for mobile telephone with full duplex operation capability
03/07/1989US4811336 Switching arrangement for communication of digital signals, in particular PCM signals
03/02/1989DE3804552C1 Door intercom system
03/01/1989EP0304674A2 Method for speech-commanded gain adjustment control in telephone transmission circuits
03/01/1989CN2033563U Coded, multiway wired microphone
02/1989
02/28/1989CA1250646A1 Communication system having multi-mode line selection buttons
02/22/1989EP0304257A2 Voice enhancer system
02/21/1989US4807225 Telephone line carrier system
02/16/1989DE3725883A1 Device for connecting and disconnecting a telephone set
02/14/1989US4805165 Time division multiplex data transmission method and apparatus
02/09/1989WO1989001277A1 Controlling key-system groups from a distributed control switching system
02/07/1989US4803718 Hold detecting and control circuit for a key telephone system
02/01/1989EP0301627A1 Digital echo canceller
01/1989
01/19/1989DE3722921A1 Method for a computer-controlled private telephone branch exchange, particularly for a key system, with the possibility of inserting an attention signal in the busy case
01/19/1989DE3722717A1 Hands-free device
01/18/1989EP0299784A2 Feature telephone integration device
01/18/1989EP0299507A2 Electronic telephone terminal having noise suppression function
01/12/1989DE3721984A1 Method for controlling voice-controlled hands-free devices of digital subscriber terminals
01/11/1989EP0298719A2 Loudspeaking telephone with a variable gain circuit
01/10/1989US4797915 Communication system having automatic call route selection
01/10/1989US4797877 Communication system dynamic conferencer circuit
01/03/1989US4796294 Electronic telephone exchange and method of connecting ports of the exchange
01/03/1989US4796287 Digital loudspeaking telephone
01/03/1989CA1248252A1 Key telephone system
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