Follow the user manual for a better understanding of use. This configuration includes one parent unit (monitor) and one baby unit (audio monitor) DECT 6.0 provides crystal clear transmission, eliminating the annoying white noise you hear from analog monitors 5-level sound indicator - graphic bars on the parent unit indicate the level of sound in your baby's room so you can visually monitor the noise level with the unit muted Sometimes all your baby needs is to hear the sound of your voice - comfort your infant with the 2-way talk-back intercom Rechargeable batteries provide the parent unit with up to 18 hours of monitoring time on a single charge, or use two AAA batteries (not included) Go hands free with the belt clip on the parent unit - carry the parent unit everywhere you go without the hassle of holding it. The operating range of the parent unit is up to 1,000 feet outdoors or 160 feet indoors Parent unit can be set to beep if: (1) link between the parent unit and the baby unit is lost, and/or (2) rechargeable battery is low Language is preset to English, but can be switched to French or Spanish for all screen displays The loop on the baby unit doubles as a soothing night light for your little one Vibrating sound-alert on the parent unit - enjoy some added peace by being silently alerted when there is sound in your baby's room The VTech DM221 Digital Audio Monitor with DECT 6.0 digital technology provides crystal clear transmission, eliminating the annoying white noise you hear from analog monitors. The only sounds you hear are coming from your baby. Totally digital transmission eliminates background noise and prevents interference so you can rest assured the only sounds you—and only you—will hear are your baby's. Make sure the Baby Unit is turned on. Move the Parent Unit closer to the Baby Unit, but not closer than 1 meter / 3 feet. If you are using the Parent Unit in cordless mode, the battery may be low and requires recharging. A full charge takes 12 hours. Reset the system by disconnecting power from both units, waiting at least one minute, then reconnecting power. Allow time for the two units to link to each other. Nearby cordless phones or other electronic devices may be interfering with the baby monitor. Separate these devices as far apart as possible. When you turn the nightlight on, if no sound is detected for 15 minutes, the light will turn itself off.