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NO121959B
(enExample)
|
|
|
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US2252766A
(en)
|
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Signaling system
|
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SE178767C1
(enExample)
|
|
|
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US541077A
(en)
|
|
Of same place |
|
US681374A
(en)
|
|
Microphone and telephone installation.
|
|
US2101699A
(en)
|
|
Alternating current signaling system
|
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US2268880A
(en)
|
|
Telephone system
|
|
US2258650A
(en)
|
|
Signaling system and apparatus
|
|
US1608522A
(en)
|
|
Composite ringer circuits |
|
US1778768A
(en)
|
|
Telephone-ringing system
|
|
US1251208A
(en)
|
|
Alternating-current telegraph and telephone duplex.
|
|
US1689598A
(en)
|
|
Telephone substation circuits
|
|
US1942404A
(en)
|
|
Telephone system
|
|
US1351876A
(en)
|
|
Semi-automatic telephone system
|
|
US669710A
(en)
|
|
Telephone-circuit.
|
|
US647300A
(en)
|
|
Telephone signaling system.
|
|
US627814A
(en)
|
|
Telephone-exchange switch apparatus and circuits.
|
|
US1441426A
(en)
|
|
Electrical rectifier and pole changer
|
|
US1291942A
(en)
|
|
Vibratory converter.
|
|
US839095A
(en)
|
|
Automatic telephone-exchange for double-wire telephone systems.
|
|
US1512933A
(en)
|
|
Signaling system
|
|
US984203A
(en)
|
|
Selective signaling system.
|
|
US942091A
(en)
|
|
Harmonic signaling system.
|
|
US1553935A
(en)
|
|
Automatic telephone system
|
|
US1612147A
(en)
|
|
Signaling system
|