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BE468418A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
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US2055647A
(en)
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Telephone line system
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US1647796A
(en)
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Telephone system
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US2292371A
(en)
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Repeater circuit
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US2299203A
(en)
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Telephone system
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US2763722A
(en)
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Busy tone circuit for automatic telephone systems
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USRE19741E
(en)
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Telephone system |
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US2024581A
(en)
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Telegraph toll system
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US2186219A
(en)
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Telephone system
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US1967404A
(en)
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Signaling apparatus
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US2745903A
(en)
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Signaling system
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US2172875A
(en)
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Telephone system
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USRE21835E
(en)
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D mitchell |
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DK141979B
(da)
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Kobling til telefonapparater med tone-trykknapvalg.
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US1818064A
(en)
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Telephone system
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US1381483A
(en)
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Telephone-exchange system
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US2173924A
(en)
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Telephone system
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SU1210231A1
(ru)
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Устройство дл автоматической переадресации вызовов
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US1963747A
(en)
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Telephone system |
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US869119A
(en)
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Telephone system.
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US2232362A
(en)
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Selective signaling system
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BE335629A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
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US2690478A
(en)
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Circuit arrangement for communication systems, in particular private automatic telephone branch exchanges
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US1392179A
(en)
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Operator's trunk-circuit
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SU1197150A1
(ru)
|
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Устройство дл служебно-диспетчерской св зи
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