Features:1) Any extension ports compatible with our two-wire key telephone and limitless quantity 2) Use it directly after connected3) Flexible extension number assignment ( 2, 3 or 4 digits)4) FSK / DTMF caller ID, internal and external caller ID transferred 5) Extension password 6) Different class for extension 7) Second outward code8) Discretional ringing extension assignment when operator attendant, two operator extensions assignment when auto attendant9) 3 pieces OGM for auto-attendant use10) Day and night service11) Extension call to operator by one touch button12) Busy transferred, unconditional transferred and do not disturb 13) Ten difference groups for extensions and CO lines14) Call transfer, three parties' conference, caller ID transferred15) Support PC call management software, have reverse detect function can have nicety bill after apply reverse detect service from telecom office16) Internal "call bill memory" and clock to ensure system can record the bill even when PP call management software is not started17) PC voice record software optional18) Remote program function to make the maintenance easierPacking:Standard export carton producing area:China payment:T/T, L/C