This is a Pakistan or India based IRS scam. Do not fall for it. The IRS does not initiate any legal action via phone.
Read http://www.treasury.gov/tigta/press/press_tigta-2014-03.htm
As general background information, here are a few things you can do:
1) Report it to TIGTA under http://www.treasury.gov/tigta/contact_report_scam.shtml especially if you have become a victim (lost money, gave personal information etc.). You can also file a complaint with the Federal Trade Commission at ftc.gov/complaint (include “IRS Telephone Scam" in your complaint). This way you can also help the government establish specific fraud patterns.
2) Help kill their phone lines. The scammers use Voice over IP lines (e.g. magicJack (Ymax corporation)) to make it seem as if they are calling from the US. This is always against these companys' terms of service and can lead to immediate termination of their contract and blocking of their IP addresses for future attempts to register. Do a reverse look up of their telephone number (e.g. www.whitepages.com) to identify the Voice over IP provider and report it to the company and or law enforcement (local police and/or state attorney general)
3) If you are really annoyed: call or write to your representative in Congress. As these scams happen all over the country maybe this will trigger a reaction and provide US law enforcement agencies with the political backing and the resources they need to work in India and Pakistan together with local authorities (it can happen, read: http://www.ndtv.com/article/india/ex-call-cen ... mmission-320427). A US task force has already been set up in Jamaica to nab scammers there (see http://www.ice.gov/doclib/news/library/reports/cornerstone/cornerstone7-1.pdf). You can use the following template for your letter (more powerful!) or email:
I got a call from this number and the person on the phone said she was an IRS officer and got a case number for me and asked me to call 202-506-9713. When I called that number, a man answered phone and he was very rude. Both woman and man had an Indian accent. Please help to track down on this kind of calls and find those who are responsible. Thanks.
I got robocall from this number at 6:15 am and told me house and assets were being seized and to call 202-506-9670 - called but voicemail sounded suspicious so didn't leave message. Called back the caller ID of 202-506-9720 and got voicemail with heavy Hindi accent saying "This is IRS leave a message." Didn't! Reported to IRS Fraud and FTC sites.