The VTech DS6151 + (1) DS6101 cordless phone system is expandable up to 12 handsets and features DECT 6.0 technology. With this technology the user can enjoy the best in cordless phone sound quality, security, and range. This system won't interfere with wireless networks and, with the enhanced security features, you no longer have to worry about identity theft . The DS6151 + (1) DS6101 has 50 station caller ID/call waiting that will let you know who is calling even when you are already on the line. Additional features include 50-entry phonebook directory, last number redial, selectable ringtones, page/handset locator, handset volume control, large backlit display and keypad. This energy star qualified phone has a digital answering system with dedicated mailbox for each line.