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)
05/1978
05/02/1978US4087649 Pulse counting circuit
05/02/1978US4087643 Time division multiplexed PABX communication switching system
04/1978
04/25/1978US4086444 Dial pulse key telephone intercom system
03/1978
03/28/1978US4081625 Control circuitry for key telephone apparatus
03/28/1978US4081624 Key telephone intercom line system
03/28/1978US4081615 Subset switching means in apparatus for a key telephone system for enabling intercom substations to access trunk lines
03/21/1978US4080517 Audio sensory apparatus and method for monitoring indicator lamp status of multi-line telephone instrument
03/14/1978US4079212 Extension telephone system
02/1978
02/21/1978US4075434 Key telephone privacy exclusion apparatus
01/1978
01/31/1978US4071712 Line circuit for key telephone systems
01/31/1978US4071710 Communication-recorder system
01/31/1978US4071699 Apparatus providing for the remote display of calling numbers in a telephone system
01/10/1978US4068092 Voice control circuit
01/03/1978US4066842 Method and apparatus for cancelling room reverberation and noise pickup
12/1977
12/27/1977US4065646 Power converter
12/20/1977US4064373 Line circuit for key telephone systems
12/20/1977US4064371 Apparatus for a key telephone system for enabling intercom substations to access trunk lines
12/13/1977US4063047 Key telephone system multilink hands free answer circuit
12/06/1977US4061887 Key telephone adapter for electronic telephone switching system
11/1977
11/29/1977US4060700 Two-party telephone system
11/08/1977US4057693 Logic control for electronic key telephone line circuit
11/08/1977US4057688 Intercom embodying tap transducers
11/01/1977US4056695 Key telephone line circuit tone-on-hold arrangement
10/1977
10/25/1977US4055731 Key telephone lamp control circuit
10/11/1977US4053720 Automatic exclusion circuit
10/04/1977US4052562 System for control of speech direction in duplex telephone circuits
09/1977
09/27/1977US4051328 Method for operating a digital time division multiplex communication network
09/27/1977US4051325 Speech intercommunication system
09/20/1977US4049921 Method for forming a conference connection in a time division multiplex telecommunication switching system
09/20/1977US4049911 Talk-through unit with voice controlled switching with turn off delay variable from 250-500 milliseconds depending on voice amplitude
09/13/1977US4048446 Data transmission system
09/06/1977US4046972 Key telephone station set circuit
08/1977
08/02/1977US4039763 Key telephone communication path interface
08/02/1977US4039762 Key telephone off-premises line circuit
07/1977
07/26/1977US4038601 Device for connecting peripheral units to a line for transmitting data by pulse code modulation
07/19/1977US4037058 Intercom system for a key telephone system
06/1977
06/28/1977US4032724 Direct station selection circuit
06/28/1977US4032714 Pcm time division multiplex communication network with digital subscriber stations
06/21/1977US4031327 Telephone set and system utilizing frequency division multiplexing
05/1977
05/24/1977US4025728 Speaker telephone
05/17/1977US4024353 Key telephone system
05/10/1977US4022985 Key telephone system with a common push-button sender system
05/10/1977US4022976 Mechanically-coupled microphone-speaker unit and intercom system
05/03/1977US4021622 Nonlocking key telephone set
04/1977
04/26/1977US4020289 Random access, multiple station communication system
04/19/1977US4018997 Pluggable key set telephone cross connect device
04/05/1977US4016372 Apparatus for a key telephone system for enabling intercom substations to access trunk lines
03/1977
03/08/1977US4011415 Call circuit for key telephone system for giving direct station selection call priority over station call
03/01/1977US4010332 Link circuit for intercom unit
03/01/1977US4010331 Telephone intercommunication system incorporating improved dialing arrangement
02/1977
02/15/1977US4008376 Loudspeaking teleconferencing circuit
02/01/1977US4006310 Noise-discriminating voice-switched two-way intercom system
01/1977
01/25/1977US4005277 Echo controller comprising a mode switch for switching echo suppressor and canceller
01/18/1977US4004106 Line circuit for use with a key telephone system
01/11/1977US4002860 Transmitting and receiving apparatus
01/11/1977US4002854 Loudspeaking telephone instruments
01/04/1977US4001517 Direct station selection hold arrangement
12/1976
12/28/1976US4000376 Telephone privacy device
12/21/1976US3999006 Visitor confirmation system
12/14/1976USRE29078 Key telephone system
12/14/1976US3997738 Line circuit for telecommunications exchange using TDM
12/14/1976US3997737 Security line card circuit
11/1976
11/30/1976US3995217 Method and apparatus for suppressing background noise in a digital telephone system
11/09/1976US3991282 Multi station telephone switching system
11/09/1976US3991281 Key telephone monobus conference arrangement
10/1976
10/12/1976US3985976 Audio frequency signalling systems for telephone systems
10/12/1976US3985959 Key telephone system for subscribers
09/1976
09/07/1976US3979563 Communication systems of key telephone systems
08/1976
08/24/1976US3976847 Key telephone system intercom arrangement
08/17/1976US3975588 Acoustic feedback control
08/10/1976US3974344 Electronic speech circuit for a central battery telephone set
08/03/1976US3973085 Key telephone system with directly associated station cards and sets
07/1976
07/27/1976US3971899 Signalling device for key telephone systems
07/27/1976US3971898 Visual indicating control circuit in key telephone system
07/20/1976US3970786 Loudspeaking telephone with improved receive sensitivity
06/1976
06/29/1976US3967076 Call denial circuit for key telephone systems
06/29/1976US3967072 Time division network connection auditing arrangement
06/22/1976US3965308 Line card circuit
06/15/1976US3963957 Lamp power supply arrangement for key telephone system
06/15/1976US3963876 Amplifier circuit for increasing transmit and receive levels in a telephone hybrid network
06/15/1976US3963868 Loudspeaking telephone hysteresis and ambient noise control
06/01/1976US3961144 Exclusion circuit in key telephone system
06/01/1976US3961142 Method and apparatus for automatically annunciating the completion of a telephone call hold interval
04/1976
04/27/1976US3953683 Interrupter for telephone systems
04/27/1976US3953676 Digital control of a loudspeaking telephone system
04/20/1976US3952169 Solid state line circuit for a key telephone system
04/20/1976US3952166 Loudspeaking telephone circuit
04/20/1976US3951248 Telephone line visual status indication circuit
03/1976
03/23/1976US3946170 Self regulating telephone sets
03/23/1976US3946146 Discrete ringing detector for use in key telephone systems
03/16/1976US3944743 Method and apparatus for feedback suppression
03/09/1976US3943301 Solid state four-wire switch for key telephones
03/02/1976US3941944 Signalling device for key telephone systems
03/02/1976US3941943 Privacy circuit for key telephone systems
03/02/1976US3941933 Paging intercommunication system
02/1976
02/24/1976US3940561 Simplex intercommunication system and a two-way intercommunication system having an electronic trunking scheme
02/17/1976US3939311 Muting circuit for subscribers telephone
02/10/1976US3937907 Digital echo suppressor
02/10/1976US3937901 Lamp control circuit for key telephone systems
02/10/1976US3937892 Electronic time-division-multiplexed pabx telephone system
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