TheNortel Meridian 1 M3902 (NTMN32) Telephone Set is designed for light telephone use with more feature requirements. They work great in areas like manufacturing areas and warehouses. The M3902 introduces the display based interface and handsfree capability to a single line phone. Enhancements such as self labeling keys, "Smart" Mute and a host of user selectable options make this a powerful single line set. The M3902 also increases its capabilities by supporting a cartridge accessory that conveniently snaps into the back of the phone.