Just recieved a call from 415-506-2399 stating she was from the IRS and if I did't call back further
steps would be taken against me. call came from Navato California just now 9.30am

I have now received two calls from this number.   Hard to understand the voice,  no real reason for the call,  just needed to call the number back to avoid further action.   IRS generally mails their requests.   It's unfortunate this continues to happen.   Don't answer, don't call back.

Got a call from Julie smith called it back and message boxes was full

Yeah, these turds called me too. They say it's from IRS but they are using magicjack I think.

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

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Do consider getting a call blocking device or phone.. You can google them and many are around $50.00 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.