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)
08/1980
08/06/1980EP0014044A1 Method and system for reducing conference bridge oscillations
08/05/1980US4216356 Telephone having separate voice and signaling pairs
07/1980
07/29/1980US4215252 Video teleconference audio echo control unit
07/29/1980US4215248 Telephone intercom circuit
06/1980
06/17/1980CA1079882A1 Pulse counting circuit for key telephone system
06/17/1980CA1079881A1 Key telephone lamp control circuit
06/17/1980CA1079880A1 Key telephone system signal priority arrangement
06/10/1980US4207439 Line/interface circuit for key telephone systems
06/10/1980CA1079429A1 Dial pulse key telephone intercom system
06/10/1980CA1079428A1 Logic control for electronic key telephone line circuit
05/1980
05/27/1980CA1078536A1 Bilateral voice-signal controller for use in the two-wire portion of the telephone circuit
05/13/1980US4203011 Computer controlled key telephone station set
04/1980
04/29/1980CA1076688A1 Apparatus providing for the remote display of calling numbers in a telephone system
04/16/1980EP0009773A1 Method and circuit for discriminating between electric speech signals or the like and frequency constant tone signals
04/16/1980EP0009626A2 Communication system for fixed and mobile subscribers
04/16/1980EP0009591A1 Circuit for a speech-controlled loudspeaking telephone station in telecommunication systems, especially telephone systems
04/02/1980EP0009461A2 Circuit arrangement for subscriber stations
04/02/1980EP0009127A1 Circuit for a line-fed loudspeaking telephone station
04/02/1980EP0009051A1 Telephone system with a plurality of internal extensions and a plurality of outside lines
04/01/1980US4196316 Program controlled communication system having individually rearrangeable line selection
03/1980
03/18/1980US4194093 Key system protective apparatus
02/1980
02/19/1980US4189624 Digital time division multiplex telecommunication network
02/12/1980US4188511 Multi-link telephone intercom system
02/12/1980CA1071784A1 Link circuit for intercom unit
01/1980
01/22/1980US4185173 Key telephone call signalling circuit
01/15/1980US4184054 Key telephone system
01/08/1980CA1069607A1 Time division multiplexed pabx communication switching system
12/1979
12/11/1979US4178480 Signal multiplexing circuit
12/04/1979CA1067636A1 Intercom system for a key telephone system
11/1979
11/20/1979US4175216 Intercom calling apparatus in a key telephone system
11/13/1979US4174466 Multi-party telephone system allowing speech connection between extensions as between extensions and an outer line
11/06/1979US4173714 Communication circuit with combined power feed and data transmission over a phantom channel
10/1979
10/23/1979CA1065072A1 Loudspeaking teleconferencing circuit
10/16/1979US4171467 Signal multiplexing circuit
10/09/1979CA1064172A1 Apparatus for suppressing background noise in a digital telephone system
09/1979
09/19/1979EP0004182A2 Improvements in or relating to audio teleconferencing
09/18/1979US4168403 Key telephone system comprising only one control lead per outside line
09/18/1979CA1062822A1 Direct station selection hold arrangement
09/06/1979WO1979000648A1 Telephone system with a plurality of internal extensions and a plurality of outside lines
08/1979
08/28/1979CA1061488A1 Control circuitry for key telephone apparatus
08/21/1979US4165445 Circuit for preventing acoustic feedback
08/14/1979CA1060594A1 Key telephone off-premises line circuit
07/1979
07/24/1979US4162374 Voice-switched telephone set
07/17/1979US4161624 Hands-free telephone with cascaded attenuators
07/10/1979CA1058340A1 Two-way loudspeaking device for telephone stations
07/03/1979US4160131 Electronic key telephone system
06/1979
06/19/1979US4158755 Telephone system open switching interval protection circuit
06/12/1979US4158112 Hands-free answer arrangement on intercom for key telephone system
06/12/1979US4158110 Tone selective key telephone intercom system including digital tone detector
05/1979
05/29/1979US4156797 Filter for voice operated triggering circuits
05/17/1979WO1979000250A1 Communication system call coverage arrangements
05/15/1979US4154981 Telephone system for diver communication
05/15/1979CA1054692A1 Communication transmission installation
04/1979
04/17/1979US4150257 Communication system call coverage arrangements
04/03/1979US4147892 Speakerphone with dynamic level discriminator
04/03/1979CA1052024A1 Line circuit for use with a key telephone system
03/1979
03/20/1979US4145579 Key telephone unit protective coupler
03/06/1979CA1050101A2 Line surge protection device for telephone lines
02/1979
02/27/1979CA1049672A1 Key telephone system line circuit
02/27/1979CA1049671A1 Key telephone system intercom arrangement
02/22/1979WO1979000078A1 Hold control for a key telephone system
02/20/1979US4140877 Muliple highway time division multiplexed PABX communication system
02/13/1979CA1048627A1 Multi station telephone switching system
02/06/1979CA1048186A1 Speech intercommunication systems particularly for hands-free loudspeaker telephones
02/06/1979CA1048185A1 Two-party telephone system
01/1979
01/23/1979US4136263 Telephone system having space divided speech channels and a separate time divided data highway
01/16/1979USRE29884 Key telephone system for subscribers
01/16/1979US4135063 Modular, expandable intercom system for a multiple-station telephone subscriber installation
01/09/1979US4133985 Key telephone system
01/02/1979US4132870 Key telephone system optically coupled protective coupler
01/02/1979US4132869 Intercommunication system
01/02/1979US4132860 Hold control for a key telephone system
12/1978
12/19/1978US4130737 Two-link intercom system
12/12/1978US4129750 Digital time division multiplex telecommunication network
12/05/1978CA1043916A1 Security line card circuit for key telephone system
11/1978
11/21/1978US4126770 Echo canceller
11/14/1978US4125749 Key telephone systems
11/07/1978US4124776 Information system having multiple access and decentralized exchange
10/1978
10/31/1978US4123620 Apparatus for controlling the sound generation in the loudspeakers of intercommunicating telephone sets in response to speech signals from the microphones of said telephone sets
10/10/1978US4119804 Open loop system for transmitting digital information
10/10/1978US4119797 Voice operated switch having an activation level which is higher than its sustaining level
10/10/1978CA1040332A1 System for control of speech direction in duplex telephone circuits
10/10/1978CA1040327A1 Active hybrid sidetone producing circuitry for sidetoneless telephone
10/03/1978CA1039873A1 Amplifier circuit for increasing transmit and receive levels
09/1978
09/26/1978CA1039424A1 Universal pbx line circuit for key and non-key service
09/19/1978US4115658 Two way telephone amplifier
09/19/1978CA1038981A1 Interrupter for key telephone systems
09/05/1978US4112261 Key telephone system and method
08/1978
08/29/1978CA1037554A1 Line surge protecting device for telephone lines
08/22/1978CA1037173A1 Paging intercommunication system
08/15/1978CA1036735A1 Digital echo suppressor
08/15/1978CA1036730A1 Station loop control arrangement for telephone switching system
07/1978
07/18/1978US4101741 Line circuit for key telephone systems
07/18/1978US4101740 Line circuit for key telephone systems
07/18/1978US4101735 Two-way loudspeaking device for telephone stations
06/1978
06/20/1978US4096358 Key telephone system signal priority arrangement
06/06/1978US4093830 Key telephone system line circuit
05/1978
05/30/1978US4092501 Key telephone system
05/09/1978US4088846 Hold-plus-intercom for single-line stations
05/09/1978US4088844 Telephone station set interface circuit
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