Having travelled to India several times, I have really needed a decent roaming product there, and searched high and low, and can assure you that there is no international SIM that gives free incoming. The only option is via call forwarding to a local. Even the numerous local SIM's I have bought, have rarely managed to pan over 2 trips because of the short validity periods. I know now for a slightly higher outlay one can get a far better prepaid product, but even then I have been stuck with cards being tied to certain zones within the country and needing to pay incoming roaming charges whilst out of state etc.
As far as I know there is not even a prepaid SIM available within India (at any price) that genuinely gives you free incoming calls wherever you are in the country. This is because the numbering range for mobiles (starting 98 ) are tied to a specific area (or "cluster" as they are known there). Take an example of this tariff list that I found of one popular provider (BPL Mobile): Their prepaid package is called "mots" (MObile on the Spot)
http://www.bplmobile.com/mumbai/mum_nat_roam.htm
It states that incoming calls are charged at Rs.1.75 whilst roaming within India. AFIK This is comparible with most prepaid "roaming" products available within India.