What's the sound in Apple's mobile phone after the Do Not Disturb mode is enabled?

Do not disturb mode is turned on, but the phone is silent when the call comes, not blacklisted, so the phone is still turned on when others call, and there is no voice prompt.

If you need to set not to answer this call, it is recommended to set a blacklist directly in your mobile phone (Settings-Phone-Blacklist-Add-Enter the phone number to be blocked).