The Compact (6X16) system is a self contained unit with 6 RJ11 jacks for the interface for the telephone lines and one male 50-pin amphenol connection is used as the interface for the stations, the amphenol is also used for the connection of external devices such as Music on Hold source, paging and a relay for auxiliary ringers. The system can be configured with up to six lines and sixteen stations non expandable. Required DS software cartridge to operate the Norstar Compact system. Its not compatible with NON- DS software cartridge.