I have received recorded messages from this number about it being important message from the IRS.  I called them back - no one spoke clear english.  I asked the location of the IRS office, the person clearly read it was the IRS headquarters at 1111 Constitution Avenue in Washington DC.  However, this number indicates the call comes from Miami. the previous number indicated the call was coming from San Diego.  I have contacted our State Attorney General's office about this potential fraudulent scam system.