RCA ViSys 25450RE3 4-Line Corded Base Full Duplex Speakerphone Expandable to 16 Handsets (Black/Silver) Extended Range - up to 2000 feet with patented high powered digital tech. Allows calls to be directed to the appropriate extension or voicemail when the base unit is unattened. Expandable Base Station - up to 16 handsets. No phone jack needed for additonal handsets. Intercom-Allows convenient 2 way conversation between handsets or between handset and base without using the phone line Call Waiting Caller ID-Display shows name and number of incoming call even if you're on the phone with another caller.