There are times when we can't take calls and we won't like to disconnect it either. It would be best to mute the ringtone. We can set it in the settings on most phones if it permits. Or you can mute using the volume down button. This works on many smartphones.
To mute the incoming call ringtone on Redmi 2 Android phones do the following:
1. Open settings
2. Find and tap Call Settings > Incoming call settings
3. At "Flip to silence ring" slide to right to enable.
Now when call comes, just flip the phone upside down to silence the ring. Thats it.