Open the MyJio app
Sign in with your Jio number
Tap the JioTunes or Caller Tune option
Browse or search for a song
Select the song you want
Tap Set as JioTune
Confirm the activation
Wait for the confirmation SMS
To change the tune, repeat the same steps
To deactivate, open JioTunes in MyJio and choose Deactivate or Stop JioTune