Yes there are companies/scammers in India that are using some kind of blockers so that you can't trace back to them. I've actually spoken to an attorney about these unwanted calls and he said there is nothing you can do about it.
Got a call from this number I have Comcast but they Do Not have this number I don't Ever give it out. I think the scammer is using a computer auto dialer dialing every number in an exchange and connecting the answered phones to the recorded msg. They won't stop and you can't shoot them!