X10 Security Systems feature an unbeatable 3-Way Protection - When the Protector Plus Voice Dialer Wireless Home Security System is triggered by a door or window sensor, motion detector, or panic button, it sounds a powerful 85dB siren, flashes lights, and calls 4 phone numbers - be it your own cell or work phone, your family, neighbors or friends. It then plays a "security alert message" (that you've recorded). If the first number doesn't answer, it phones the next, and so on - and it's not fooled by answering machines. Once someone is reached, they can listen in to your house directly through the Protector Plus Voice Dialer.