NEC 1090001 DSX40 Key Service Unit (Refurbished)Key Features: Mfr. Part #: 1090001 NEC DSX Key service unit Initial 4 x 8 x 2 Contains: central processor, power supply, (4) central office line ports, (8) DSX digital key telephone ports, (2) conventional analog telephone ports Also contains interface circuits for (2) analog door chime boxes (including relays) Maximum system capabilities: (8) lines x (24) digital stations x (2) analog stations (8) lines x (16) digital stations x (10) analog stations