After getting these calls, I searched online and found that like me large numbers of people are getting such calls. Generally, no callers of these calls say anything to me and others; though, there are also some insistences where people were told about winning a contest or lucky draw. Overall, all these calls look to be very suspicious and filled of bad intensions; therefore, my advice for every person in India is to avoid taking such calls.
In the present world of internet telephony many people are using such numbers to exploit other ordinary people. Best strategy against such calls and people is to go these calls unnoticed without picking them and if you pick a call then do not accept any offer giving by such unknown callers.