Well a long time ago we did have the 1 paisa messaging which is still active today, with the users who registered with it then.
Then AirTel/Hutch PrePaid introduced the SuperValue pack @ Rs. 60 per month with 1500 free sms and half call rates. The monthly charge is now Rs. 66 I think. And you get half calling rates and 10 paise messaging. You have to do this through topup.