- 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- (8) lines x (8) digital stations x (18) analog stations- Compatible with the 4 or 8 port DSX IntraMail (1091011 and 1091013) and the 4 or 8 port DSX IntraMail Pro (1091051 and 1091053)NEC1090001