Capacity: Card Expandable Structure From 2 to 6 CO lines, 4 to 32 Extensions. 2CO line ports in each CO line card, 4Extension line ports in each extension line card Main Functions: 1. Support CTI software 2. Any extension port can be connected with our key telephone ( or single line telephone) , plug and play 3. Caller ID transferred 4. Auto detect Fax Signal 5. Outward code dialing ( least cost route, can save call fee) 6. Auto add IP code when dial long-distance call 7. Outside ( CO ) Line Duration Time Limit 8. Station lock ( personal password, allows lock your extension) 9. Busy transferred 10. Unconditional Transferred 11. Call Transferred to Secretary 12. Do Not Disturb( DND) 13. Day and Night service 14. Twin routes 3pcs OGM for DISA, total 30 seconds. 15. Party Conference ( between 2 extensions and 1 CO line ) 16. Party Conference ( among 3 extensions) 17. Executive busy override 18. Monitor voice record 19. Enable/ disable outside caller reaches extension by one touch dialing 20. Hot line ( Call to operator as soon as lifts handset without any number input ) 21. One touch dialing, allows call to operator by one key 22. Outside line ring by turns( allows assign extension ring by turns when has outside call) 23. Allows has maximum of eight extension ringing at the same time 24. Extension outgoing call class 25. Extension free notice 26. Extension number assignable freewill ( 2, 3 or 4 digits) 27. Self-Extension Number Confirmation 28. Various Outside ( CO ) Line Access Mode Selection 29. Make outside call by code ( speed dialing, increase your work efficiency) 30. Remote program, more convenient and easy after service. 31. External music input as holding music 32. Broadcast 33. Pulse and Tone mode setting 34. Polarity Reverse Detection 35. PC Billing function, also can program function by PC, etc. 36. Power switch, compatible with internal back-up battery ( option) 37. Allows rack mount or desktop