Not working?

Start by checking the following:

 

Settings

Push the top button to increase the sensitivity.
65 dB: Red light
75 dB: Orange light
85 dB: Green light

Power

Make sure the batteries in the Baby monitor are not depleted.

Phone position

Try to move your mobile phone closer to the Mobile phone transceiver.

Transceiver position

Try to move the Mobile phone transceiver closer to the Baby monitor.