AT&T 1070 4-Line Expandable Corded Phone System with Caller ID/Call Waiting and Speakerphone, 1 Handset, Black/Silver

4 line operation. Compatible with as few as 1, and as many as 4, telephone lines
32 Speed Dial and 16 Intercom;Chain Dialing
3-Party Conferencing
Speakerphone; Product does not work on a digital line, Refer user manual below.
Handset, Speakerphone, Headset and Ringer Control Volume
DSL Subscribers may need to us a DSL Filter