1. After turning on the mobile phone, we can see that HD is displayed in the upper right corner of the screen, which means that the HD voice call function of the mobile phone is turned on.

2. To turn off this function first, we need to enter the setting interface of the mobile phone. Turn on the phone and find the "Settings" function on the phone.

3. Click "Settings" to enter the following setting interface, and find "Phone" in the interface.

4. Click "Phone" to enter the phone setting page, find "VOLTE Call" in the setting page and turn it off. At this time, we will find that the HD in the upper right corner of the phone screen has disappeared.