I bought a Matrix prepaid sim card at Mumbai airport that was "preactivated". This was for UK and the plan had "free incoming".which as it turned out later was that anytime someone tried to call me they would not be able to connect and I would get an SMS stating their number and saying I had a missed call from this number. I called up their customer support and was told that their was no network issue and they were unable to provide any help.
This is a clear fraud. I would strongly advise everyone to stay as far as possible from this mobile operator.