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Marc F: 400D Central Office or PBX Line Circuit KTU
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Marc F: 401A Manual Intercom Line KTU
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Marc F: 422B Station Busy Selector KTU
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Marc F: 426A
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Marc F: 427C
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Marc F: 407C Dial Intercom 10-Code Selector KTU
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Marc F: 415B Automatic, DC Signaling Private Line KTU
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Marc F: 451B Music on Hold KTU