Make sure the light on the chime is flashing green. If not, please press the set button on the chime for 3 seconds to put it into pairing mode.
Try to put your phone close to the hole on the chime. It is where the microphones used to receive sound locate.
Try to send sound waves from different distances.
If you have tried several times and still not heard anything from chime, unplug the chime and plug it back in. After you hear System Ready, press the set button for 3 seconds to go into pairing mode, and send the sound wave again. Rebooting the chime helps increase the chance that the chime recognizes sound waves. We don't suggest you try sending the sound wave too many times without rebooting the chime.
If the WiFi name and password are too long, or they include special characters, it will be harder for the chime to recognize the sound wave. In this case, consider temporarily changing your WiFi name and password. After successful pairing, upgrade the firmware using the WUUK app to the latest version. The new version of firmware supports pairing with QR code. You can change your WiFi name and password back and start the pairing process again with QR code.