For my Thailand Trip, I got a Matrix SIM from Kolkata Airport. I was told there are 15 free minutes to India every day. However, when I got the bill I was charged 25 THB per minute.
When I spoke with their Customer Care, they told you have not dialed the number correctly; They said there should be a code used for getting the free minutes to India. While buying SIM card I was not told by the Matrix people that I should dial the India number with a code. They are actually cheating the people with this technique. Please avoid Matrix, better take SIM from the Visiting Country.