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DK142220B
(da)
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Kobling til teleanlaeg i hvilke forbindelsesveje kan benyttes til forskellige arter af informationsoverfoering
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US2909607A
(en)
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Automatic telephone system with automatic transfer
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US2819345A
(en)
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Device for waiting within automatic telephone exchanges
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US3182134A
(en)
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Circuit for interconnecting a number of calling lines
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US2959642A
(en)
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Telephone system
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US2714630A
(en)
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Private automatic branch exchange
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US1110027A
(en)
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Telephone switching system.
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US2335481A
(en)
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Telephone system
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US3378642A
(en)
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Line lockout circuit
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US3231678A
(en)
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Subscriber controlled conference circuit
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US2185287A
(en)
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Telephone system
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US3176082A
(en)
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Telephone ringing signal transfer device
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US2619550A
(en)
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Telephone extension control system
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US2395155A
(en)
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Telephone system
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US2020816A
(en)
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Automatic telephone system
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US2657273A
(en)
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Sender overload control
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US1651017A
(en)
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Party-line revertible ringing system
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NO116699B
(enExample)
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US2815404A
(en)
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Connection for automatic ring signal
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US2913532A
(en)
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Connector circuit
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US972329A
(en)
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Lock-out device for party-line telephones.
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US2310481A
(en)
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Two-way trunk circuit
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US1928849A
(en)
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Automatic and semiautomatic telephone plant
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US2848553A
(en)
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Ringing device for telephone systems
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US2590945A
(en)
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Trunk circuit
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