Thanks Arun, that is exactly what I had been looking for.
Yes, you can do that with your own mobile number, where you can may be connect the phone to the computer and using some software get the commands from users like NEWS and then reply them with the latest NEWS.
But this won't work as a business model, you will be providing a free service to the users, they SMS using their operators, thus their operators charge them and you get nothing. While if you talk to the operator and make some partnership or pay them (I don't know how it works) then the operator can serve as your payment gateway.
So, if you set the price for a ringtone rs. 7 or 10, the operator charges the customer and pays some % to you (I don't know howdo they fix it). Same goes with the amount charged for each SMS sent for other services like News, score, etc.
I just wanted to share the info with people who doesn't know about it. If you or someone else know more about it, please let me know.
Thanks