FREE CALL BACK SMS TO ANY AIRTEL NUMBER TRICK

This is a free service given to the airtel users if the balance is below one rupees.you can send daily 3 call back sms free each day.this can be send to only the airtel numbers.for this trick SEND A SMS TO 121 LIKE THIS SMS CALLMOB NO. TO 121 Then conformation sms will be receaved when the sms send succussfully.