How about we start pricing SMSes incrementally? Each SMS will have a price xn where n is the nth SMS of the day, and x is a modifier of TRAI's choosing. For example, if the modifier is 1, the first SMS of the day will cost Rs 1, the second Rs 2 and the third Rs 3 and so on. The total cost for the 3 messages will be 6."
Link to Original Source