a) Ensure your device and mobile phone are within the 8-10m BT range to each other
Make sure device is charged properly. Low battery level may cause the disconnection from the mobile
If the battery level is less than 10% charge the device
 Note: Sometime battery percentage visibility is subjective to Mobile Phone brand

b) Power OFF and Power ON the device then again connect it with Mobile Phone

c) Set your Mobile Phone to Airplane Mode and then again set to normal mode, mobile's BT working will back to normal if any small bug is there with BT's working. If succeed then ok otherwise move to step- c

d) Restart mobile phone to refresh Mobile Phone's working and Mobile RF will also back to normal.
If Restart is not available then Power OFF and ON the Mobile Phone.
 Now again try and follow the pairing process

e) RESET the device

1- Remove device name from Bluetooth Interface
2- Open the charging case and let the buds stay in
3- Press and hold the reset button for 7 seconds
 4- the LED on the buds will blink 5 times indicating the buds have been RESET then repeat the pairing process.