The AT&T ML17929 can dial and receive calls on two different phone lines (if connected). A speakerphone lets you speak and listen handsfree, so you can do other things and others can participate in the conversation. 3-Party Conferencing allows you to have a 3-way conversation between you and people on 2 other lines. The 2 other lines can be inside lines, ouside lines or a combination. | AT&T 2-Line Corded Phone (ML17929)