If our Xiaomi smartphone receives a call we can't answer at the moment, we have the option to send a short message. This contains a short information that we are calling back or can't talk at the moment. We can customize and edit the messages as we wish.

Android 10 (MIUI 12.0)
Step 1:  Open the  Phone app
Step 2:  Open the  Settings
Step 3:  Tap on  Advanced settings
Step 4:  Tap on  Quick responses
Step 5:  Enable or disable  Quick responses
  1. Open the Phone app
  2. Open the Settings
  3. Tap on Advanced settings
  4. Tap on Quick responses
  5. Enable or disable Quick responses

Xiaomi Instructions