Just in case you haven't done it so far: check this list of SMS Gateways; many of them operate in India:
http://en.wikipedia.org/wiki/List_of_SMS_gateways[
^].
I heard that some free-of-charge SMS Gate services are emerging, try to find some:
http://bit.ly/wXCqnB[
^].
Sorry if this advice is redundant. As I say: just in case. :-)
Now, the advice by Rajeev Jayaram can be good it Way2SMS really provides as Web service. But, from a first glance, I could not find a sing of it. In this case, you can simulate the input by a human customer using the technique similar to
Web scraping. Please see my past answer for further detail:
get specific data from web page[
^],
How to get the data from another site[
^].
—SA