Craig is right Galen.. that is the real IRS.. not a scam number. Its not unusual for these scammers to use and abuse the real numbers along with their obviously sad and sorry extortion attempts and they have used the real IRS number to appear legit when they are not!  Most of these calls do come from India and Pakistan.

http://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
http://www.treasury.gov/tigta/contact_report.shtml
http://800notes.com/forum/ta-8c2f64bf2b91fa5/irs-warns-of-telephone-scam

http://bigstory.ap.org/article/4b849c65e54346 ... leader-irs-scam

Report the Calls to the real IRS here:
•report the incident to the Treasury Inspector General for Tax Administration at 800-366-4484.
•You can also file a complaint with the Federal Trade Commission at FTC.gov. Add "IRS Telephone Scam" to the comments in your complaint.

To file complaints on Foreign company's and scams:
http://800notes.com/forum/ta-d20d86fdc3e145c/reporting-international-scams
https://www.econsumer.gov/#crnt
eConsumer.gov: Report Your Complaint
E-mail: econsumerwb@ftc.gov
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Do consider getting a call blocking device or phone.. You can google them and many are around $40.00 or so.If its a cell phone, some already have call blocking, if not, there are free apps on the web that will work for some. You can google this. If you have a smart phone, there is a free app called call control. Iphones appear to have apps also. Another one is called Mr. Number.

For tracfone & straight talk:

https://play.google.com/store/apps/details?id ... .tracfone&hl=en
http://extras.straighttalk.com/en
http://www.youmail.com/home/carriers/straight-talk/block-number
https://www.straighttalkwirelessforum.com/viewtopic.php?f=6803&t=55006