I received this call too.  Seriously!!  Can the IRS not track this ignorant people?

These "ignorant people" are more than likely overseas so even if the IRS could track then, there's nothing they could do once they found them.

They leave a voicemail saying there are serious allegations against me and I'm gonna be taken into custody by the local "cops."

Just a stupid Scam.  Even the IRS has published information on this.  see MoneyScam.info

I just received a call from 720 571 7825  with very similar messages to the below.
IE - issues with my tax returns from years back - that the authorities are waiting to lock me up etc.  After a few moments of panic - it set in the the IRS doesn't work this way.  Again - I had some Indian guy telling me that I was going to jail.....