You can update your watch by following these steps:

• Connect your watch to the phone using the Da Fit App. Open the Da FIt app, go to devices and then go to Update. Follow the onscreen instructions to update your watch.
• Check the network signal quality of the area where the user is located. The call signal may be poor if the network connection is not stable. Advise the user to try making calls in an open area with stable network connection.
• If the issue persists, unpair your watch from the phone, then pair the watch with another phone, and try again. If issue can be well received, it indicates that there is an issue with your phone's Bluetooth. It is recommended that you change another phone. If the issue still persists, this is an issue with your watch's Bluetooth.