The M3904 Professional phone is the ideal choice for busy executives, managers, and administrators - anyone who needs maximum flexibility in a multi-line phone. It provides enhancements in several areas including offering the largest display in its class, Personal Directory with Call Log and a variety of user selectable options. The M3904 also supports a PC utility Cartridge that allows you to create a directory of up to 100 names and then download them to your phone. The M3904 sets a new standard for user empowerment, productivity, and lower cost of ownership. Use with your Nortel PBX system.