Accessory handset only requires a Vtech DS6151 series phone to operate. Two-line operation allows you to dial & receive calls on two different phone lines with one phone. With the touch of a button, the handset speakerphone makes hands-free conversations easy. Know who's calling with Caller ID / call waiting. Handset displays the name, number, time & date of incoming calls. It store 50 calls. The 50-name / number phonebook directory lets you easily store & dial frequently called numbers. With the blue backlit keypad & display, the entire keypad illuminates along with the LCD, allowing easier viewing in dim light. Hearing aid-compatible, RoHS-compliant handset also features any key answer, intercom between handsets, transferring calls between handsets, conferencing between an outside line & up to four cordless handsets, last number redial & selectable-ring tones. Trilingual prompts allow you to choose between English, Spanish & French.