SL1100 24-Button Full-Duplex Backlit Display Tel (Black), Features include:, Abbreviated Dialing/Speed Dial, Account Code Forced/ Verified/Unverified, Account Code Entry, Alarm, Alarm Reports, Alphanumeric Display, Analog Communications Interface (ACI), Ancillary Device Connection, Answer Hold/Automatic Hold, Attendant Call Queuing, Automatic Release, Automatic Route Selection (ARS/F-Route), Background Music, Barge-In, Battery Backup - System Memory, Battery Backup - System Power, Built-in Automated Attendant, Call Arrival (CAR) Keys, Call Duration Timer, Call Forwarding, Call Forwarding with Follow Me, Call Forwarding, Off-Premise, Call Forwarding/Do Not Disturb Override, Call Monitoring, Call Redirect, Call Waiting/Camp-On, Call-back, Caller ID Call Return, Caller ID, Caller ID - Flexible Ringing, Caller ID - Shared Logging, Central Office Calls, Answering, Central Office Calls, Placing, Class of Service, Clock/Calendar Display/Time and Date, Code Restriction/Toll Restriction, Code Restriction Override/ Toll Restriction Override, Code Restriction, Dial Block/ Toll Restriction, Dial Block, Conference, Conference, Remote, Conference, Voice Call/ Privacy Release, Continued Dialing, Data Line Security, Delayed Ringing- Department Calling, Department Step Calling, Dial Pad Confirmation Tone, Dial Tone Detection, Dialing Number Preview, Digital Trunk Clocking, Direct Inward Dialing (DID), Direct Inward Line (DIL), Direct Inward System Access (DISA), Direct Station Selection (DSS) Console, Directed Call Pickup, Directory Dialing, Distinctive Ringing, Tones and Flash Patterns, Do Not Disturb (DND), Door Box