100% Working free BSNL dialer tones trick.
Due to server error now BSNL tunes ( dialer/hello/caller ) tunes arefully free and you can select more than one song a day.
Step-1: Sms your movie or song name to 56799{ toll free so dont worry} 
Step-2: Now you get a search result sms then you send sms as 1 or 2 or 3 for your liked song.
Step-3: Now you get an thank you sms and then get a sms like this your request not set due to low balance but no matter for this now your caller tunes has been set.
Enjoy this trick.
Important notes:Your balance must be below rs.3. This tricks is really working on my BSNL student plan 9486xxxxxx sim.