They called my cell which has no caller ID.  They leave a poorly computer generated (female voice) message.  It talks way too fast with no pauses at all.  It is possible that they started before my voicemail began recording.  This is my best attempt at a word-for-word transcript, "hi, this message is intended to contact you.  This call is regarding an enforcement action by US treasury.  Intending your serious attention.  Ignoring this will be an additional second attempt to avoid initial appearance before magistrate, judge, or the grand jury for a federal criminal offense.  Our number is area code 214 452 4181.  We advise, please, cooperate with us, and help us to help you.  Our number is area code 214 452 4181.  Thank you."  Horrible grammar and phrasing.  Hard to clearly make out their own phone number as well as a few words.

Poor grammar and a computer voice lead me to believe we have a scammer who has a poor grasp of the English language.  Probably, redirected to a foreign scam call center, or a recent immigrant (according to the IRS links discussed below).

I didn't bother to call back as I know the SCAM.  The phrase "US treasury" makes me all but certain that this is an IRS SCAM call.  If you're wondering... yes 100% scam.  Google "how does an IRS scam work" for details of these scams.  There are a couple of decent write-ups under the links containing "irs.gov".

They called & left a voice message. All I got was silence & then a female voice that said "good bye".
Phone number says it is from Dallas TX.

Received a call from this number today on my cell phone while I was at work. I answered because I have family in Dallas, Tx.  I was unable to understand what it was saying and sounded recorded and background sounds like police scanner noises.

Fake IRS calls meant to scare you into giving them money...but instead, do this...
Call them repeatedly, when they disconnect call them again. I have managed to keep one guy on the line for over an 1 hour before I told him I wasting his time...then when he cussed and hung up, I had a dialing app call him repeatedly and play "It's a small world" . I just got a call from this particular number today, but have shut down (had them disconnect) 4 other numbers from my harassment of them! Look, I know not all of you have the time, but for every time we call them, that's one less call that particular marketer can make. Some of you are tech savvy enough to do this and worse! We should screw these scum up as much as possible!