Hi
chinpeng930415,
Please make sure to update to the latest firmware version WW-16.0420.1912.16.
Do you mean the call will end itself and hang up? What app are you using to call? Does it appear when you call different people?
If you're using the preloaded calling app, please check with your carrier about this issue and make sure the signal is normal.
Does it appear on third party apps? Please tell us the app name and version.
Thank you
🙂