Cortelco 4 line telephone. Replacement for ITT-4125BK. Much more than just a telephone; its a system within itself. Expandable to 16 telephones and up to 4 lines requires no complicated wiring or background equipment (everything needed is built into the phone). Provides features and functionality that traditionally have been available only in more complicated and costly systems. Expandable to 4 lines and 16 stations. Caller ID call waiting caller ID on all 4 lines. 50# Caller ID directory. Visual message waiting indicator. Paging (individual or all page). Call transfer. Station status indication. Full featured intercom. Hands free speakerphone. 3-Way call conference. Large backlit liquid crystal display. Memory dial. Toll restriction. Call privacy (on/off). 2.5mm Headset jack. Redial (last 5 numbers). Do not disturb. Automatic line selection. Call timer. Private line compatibility. Static memory. Adjustable volume controls. Distinctive ringing. Dual color line status. Flash/hold/mute. Individual ringer control. Predialing. Desk or wall mountable. Hearing aid compatible. Black.