India is a long way to trace a call, not that it could even be done, since the number is probably not where the call originated to begin with, but instead is spoofed. Until the telcos make spoofing illegal, we'll never be able to trust our caller ID.
I just received the same type of call and said the same thing. Now I am getting calls marked private and when I answer it rings one time and then the call ends. One of the 2 has been calling all day and about every 45 minutes