Hybrid Key Telephone System: Capacity: D848: 4+16 extendable to 8+48 D168: 4+8 extendable to 16+128 D288: 4+8 extendable to 32+256 Features: 1. Account Code Entry 2. Automatically Call Back 3. Back-up Battery 4. Charge System & PC Port 5. CO to CO with Password 6. Class of Services 7. Call Hold Retrieve 8. Call Forward on Busy/No-answer 9. Call Splitting 10. Day/Night Services 11. DISA 12. Double-color Light 13. External Music 14. Extension Password 15. Intercom Caller ID & Transfer 16. One-touch Dialing 17. Ringing Pattern Selection 18. Paging 19. Setting Operator 20. Trunk number integrated 21. Voicemail System Compatible 22. Wake-up Call 23. 0.2% failure rate