I've gotten a few calls from 661-759-2960.  The caller, who can barely speak English and sounds Filipino, identifies himself as Derek Graham, employee ID 768519, from the US Treasury legal enforcement department, warning me that a lawsuit is going to be filed against me and that I need to call 661-759-2960 and speak with his superior Robert Matthews. I've had IRS problems in the past, so the first time this guy called, I got spooked and asked to speak with someone who could speak English and got some gobbledygook answer.  He/they have left a couple of messages on my answering machine.  This morning really got me curious because "Graham" called me three times before 7AM.  I did Spokeo and Google searches and came up with nothing to go with the number except the town, Wasco, CA which has a prision.  I then Googled "US Treasury scams" and immediately found a notice dated March 20, 2014 about a scam exactly like the phone calls I was getting.  The notice said that 20,000 people have been scammed out of $1 Million by these [***] and that the IRS does not call people, they send letters (paper trail).

http://www.treasury.gov/tigta/press/press_tigta-2014-03.htm

I also received 3 calls on my answering machine from the same number. Same circumstances, heavy accent, US Treasury, threatening legal action and possible jail time. I had a tax issue resolved several years ago. I called the Treasury and was informed that they have no connection to this number. When they called again today I picked up and told him I called the IRS and was informed that he was a scammer. I informed him I was a retired cop and that he was going to jail if caught. I gave his number to the PD and IRS. He yelled at me and hung up the phone.

I received two calls from this same number today. I never had any trouble in the past with the IRS and became nervous when I heard the threating message. I googled the IRS website and found the same public notice you posted
http://www.treasury.gov/tigta/press/press_tigta-2014-03.htm
I then googled the phone number and thankfully found that it must just be a scam.

Got same message: "Yew in Beeg trouble with Department of Treasury....meesgter Dwight...much leegal action for yew! Yew must call my boss at theese number....right away! I am paralegal Lee Boski...yew in Beeg trouble..."

Same, here just got a call.  He did not say US Treasury or IRS I don't think as I could barely understand the message.  But if definitely said legal department.  The message was worded in such an unprofessional way with vocabulary that a professional would not use but more like a high school kid would say.  "you are going to be in trouble" What professional person from a legal dept would use that terminology.  And the threats if I don't call him back.  Again unlikely to say this. Crazy.