Fraud or Fake call receive daily. How to stop them ?

Now days we are receiving fake or dummy call from unauthorised number. They try to take bank info for sending fund to our account. Most of the time, old parents they are caught into their trap.

Even by installing Truecaller we can identify this call to some extent but old parents they could not recognise this call. (DND Activation is not helping in this case)

Any idea or suggestions on how to stop these calls or messages.