2-Line Operation, Caller ID/Call Waiting 18 Number Speed Dial, 100 Name/Number Phonebook Directory Speakerphone 99 Name/Number Caller ID History DSL Subscribers may need to us a DSL Filter. Please refer the User Manual & the Quick Start Guide before use. Built-in speakerphone lets you multitask as you talk. 2-line operation offers flexibility for your home or business Caller ID/Call Waiting lets you know who's calling. Features a 99 name/number Caller ID history for easy scrolling and callbacks. Service required from your local phone company 3-party conferencing for quick remote meetings 18-number speed dial for your most frequently dialed or emergency numbers, DSL Subscribers may need to use a DSL Filter. Please refer the User Manual & the Quick Start Guide before use. 100 name/number phonebook keeps your contacts handy, Includes selectable ringer tones for each line . The ATT(R) ATML17929 Two-line Speakerphone has the most popular features, including 2-line operation, hold, memory match, 3-way conferencing and Clearspeak(R) dial-in base speakerphone.