text: if bsnl dataone connection is activated on 10th jan., what free usage in jan.will be allowed ?   you didnt tell about your plan(500 or 250) anyway ..you have only 22 days after activation so you will be having    (total free usage /  total no of days in the month) *  (the days after activation)  for example if your free usage is 1gb for january month then        (1024 mb*/31)*22 = 726.7 mb or 744150.7 kb