- Multi-line phone with three-line x 24-character display
- Personal Directory and Call Log
- Two line telephone with conference key – conference both lines for a meeting
- Fixed feature keys: Hold, Goodbye, Volume Control, “Smart” Mute and Headset w/LED, Options, Message, Call Log (Includes Redial), Applications, Shift
- Handsfree with LED
- Direct-connect headset port
- Supports up to two snap-in cartridge accessories for the Analog Terminal Adapter (ATA), External Alerter & Recording Interface, and Personal Directory PC Utility.
- Or add the Full Duplex Handsfree Accessory (with phase 3 M3904 only) or the Computer Telephony Interface Adapter (Meridian 1 only)