Open the Vi app or Vodafone Idea app
Sign in with your Vodafone number
Go to the Caller Tune or Vi Caller Tune section
Browse or search for a song
Select the song you want
Tap Set as Caller Tune
Confirm the activation request
Wait for the confirmation SMS
To change the tune, repeat the same steps
To deactivate, open the Caller Tune section and choose Deactivate or Stop Caller Tune