We are listing below the procedures to activate the ,Airtel is offering its default tone while Tata Docomo is offering the song of your choice.
Airtel:-
Airtel users need to dial the following ussd code *678*559# after you dial the Ussd code you will get a Message “Press exit to continue” press exit and you will get a new window “Thank you for choosing hello tunes service,you will be subscribed in Rs 0 for 10 Days” Reply with one and confirm the activation,once hello tune gets activated you will get a confirmation message.
Docomo:-
Docomo is offering free callertune with song of your choice for 3 days ,to activate it just dial *678# you will get the song list along with the message “Set FREE Call Me Tune song for 3 days” scroll through songs from more ,once you select a song you will get a confirmation number reply to that number and confirm your subscription.
You can deactivate the caller tune any time by just dialing a toll free number 155223 from your mobile,following the instructions and respective keys,Alternatively send an sms STOP TO 155223 And deactivate it following the instructions.