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| Patents for H04M 9 - Arrangements for interconnection not involving centralised switching (8,105) |
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| 01/27/1976 | US3935396 Key telephone system using time division and space division control | | 01/20/1976 | US3934098 Telephone message transfer circuit | | 01/13/1976 | US3932711 Transmission of voice or sound through telegraphy | | 01/06/1976 | US3931479 Telephone intercommunication system providing common access to a communication line | | 01/06/1976 | US3931478 Telephone intercommunication system provided with a common communication line to which access is guarded |
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