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Key telephone system
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Patent number 4,412,102
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Issue date Oct 25, 1983
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Nippon Telegraph & Telephone
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Seiki Ogawa
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H04 - ELECTRIC COMMUNICATION TECHNIQUE
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Key telephone system
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Patent number 4,347,409
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Issue date Aug 31, 1982
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Nippon Telegraph & Telephone Public Corporation
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Seiki Ogawa
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H04 - ELECTRIC COMMUNICATION TECHNIQUE
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Data transmission apparatus
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Patent number 4,341,927
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Issue date Jul 27, 1982
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TIE/Communications, Inc.
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Tsuyoshi Shinoi
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H04 - ELECTRIC COMMUNICATION TECHNIQUE
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