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US4730312A
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Voice, data or both over one telephone line in a T-1 carrier system
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US4503578A
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Brush assembly apparatus for cleaning cannons
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US4135063A
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Modular, expandable intercom system for a multiple-station telephone subscriber installation
|
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US4075434A
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Key telephone privacy exclusion apparatus
|
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CA1055175A
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Line card circuit for key telephone system
|
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US4008379A
|
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Touch-pad to dial conversion unit
|
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US3997737A
|
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Security line card circuit
|
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US3965308A
|
|
Line card circuit
|
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US3965306A
|
|
Telephone line transfer circuit
|
|
US3953683A
|
|
Interrupter for telephone systems
|
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US3919487A
|
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Telephone instrument disconnect circuit
|
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US3934098A
|
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Telephone message transfer circuit
|
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US3852537A
|
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Telephone station disconnect device
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US3721768A
|
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Ground start adapter unit
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