Omg, I got the same call a few minutes ago, and my heart skipped a beat because I file my taxes. Since it's after 5p.m. noone is answering the number as I'm trying to call it back. I will call the IRS in the morning to ensure that this is a hoax. Hopefully they haven't called my extended family and elderly parents -which would worry and upset them tremendously.
Don't worry about it. It is a scam. The IRS does not notify anyone of anything by phone. Calling the IRS will be a waste of your time but if you do call don't call the number the scammers gave you; find the IRS # on the net and call them.
These are bottom feeders trying to scam you. I asked him if he was from India. He said. "I hope so" I then told him to eat a cow or mate with one. Karma will get him one day for praying upon innocent people. You are fooling yourselves if you think the FTC will be able to do anything about these foreign countries spoofing US phone numbers. If you can block the phone #'s, it is the only way you can possibly ignore these horrible excuses for a member of the human race.
Actually, even though many of these boiler rooms are located outside of the US, the FTC actually can go after US-based runners for scammers based abroad. See this CNN story: http://www.cnn.com/2015/03/13/us/irs-scam/