On the Xiaomi smartphone, we can not only use standard ringtones for calls, but also choose our own custom ringtone, like a song, for example.

It is not necessary to copy the ringtone to the "Ringtones" folder, as was common in earlier versions; the user's own ringtone can be saved as desired on the internal memory or memory card.

Android 10 (MIUI 12.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Sound & vibration
Step 3:  Tap on  Ringtone
Step 4:  Choose a  SIM card   (Dual SIM)
Step 5:  Tap on  All ringtones
Step 6:  Tap on  Choose local ringtone
Step 7:  Tap on  File Manager
Step 8:  Choose an  audio file/ringtone
Step 9:  Tap on  OK
  1. Open the Settings
  2. Tap on Sound & vibration
  3. Tap on Ringtone
  4. Choose a SIM card (Dual SIM)
  5. Tap on All ringtones
  6. Tap on Choose local ringtone
  7. Tap on File Manager
  8. Choose an audio file/ringtone
  9. Tap on OK

Xiaomi Instructions