I received a phone call on my cell phone today, 7-18-2014 from 202-506-9863 stating they were from the IRS in Washington, DC. If I did not call them back they would take immediate legal action

I got a phone call around that same time I answered and they said it was the irs

This a Pakistan based IRS scam (there are also Indian based ones). Do not fall for this. Read http://www.treasury.gov/tigta/press/press_tigta-2014-03.htm
The IRS does not initiate any legal action over the phone. Report it also to your local law enforcement agency. The scammers use voice over IP lines (e.g. magicjack (Ymax corporation). This is always against these companys' terms of use and can lead to termination of their contract. However only law enforcement can initiate the contact if you yourself are not a customer. Ultimately this is a case for the FBI legal attache in Islamabad. 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 the NSA can finally be a force for good).

So, what else is new?  It's a screwed up, dog eat dog world out there.  If they call back, ask them to hold on and put the phone down, with an open line and walk away.  Let them stew.....waste their time.  Live your life...forget them.

I just checked my messages, actually gave me a heart attack.  Message from 202-506-9863, recorded message saying call IRS, if I didn't return this call, they would take action.  They also left a name Heather Gray.