Make sure when you start the pairing process, first unplug the chime and plug it back in. Wait until you hear "System Ready" from the chime.
Please press the set button on the chime for 3 seconds to put it into pairing mode, until you hear "Ready to Scan" or "Ready to Pair".
Try to put your phone close to the hole on the chime. It is where the microphones used to receive sound locate.
Make sure turn the speaker or audio volume up on your mobile phone devices.
Try to send sound waves from different distances.
If you have tried several times and still have 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, or pair it with another WiFi network if one is available. After successfully pairing and getting the system online, upgrading the firmware using the WUUK app to the latest version should help solve the pairing issue, so you can pair it with the designated WiFi network of your choice.