Features: 1) All the ports enable compatible with our two-wire key telephone at the same time, use it directly after connected 2) Flexible extension number assignment ( 2, 3 or 4 digits) 3) FSK / DTMF caller ID, internal and external caller ID transferred 4) Extension personal password 5) Different class for extension 6) Second outward code 7) Discretional ringing extension assignment when operator attendant two operator extensions assignment when auto attendant 8) 3 pieces OGM for auto-attendant use 9) Extension call to operator by one touch button 10) Busy transferred, unconditional transferred and do not disturbance 11) Ten different groups for extensions and CO lines 12) Call transfer, three parties conference, caller ID transferred 13) Support PC call management software, have reverse detect function can have nicety bill after apply reverse detect service from telecom office 14) Internal Call Bill Memory and clock to ensure the system can record the bill even when PC call management software is not started 15) PC hard disk voice record software optional 16) Remote program function to make the maintenance easier