Four-line accessory handset is designed for use with AT&T Four-Line Corded/Cordless Small Business System with Extendable Range and displays four lines. Design includes push-to-talk speakerphone and 50-name/number Caller ID history, 100-name/number phonebook directory, volume control, ringer volume control, low-battery indicator, intercom, mute, redial, hold function and 10-name redial.