There is a quick way to defeat these clowns and get them to disconnect their line. If you have a few minutes and want to have some fun, call them back and prank call them.
  It pisses them off, they curse and then I call back and call back on several different phones and do the same thing. it takes about 5- 10 mins
 I've done this now with several numbers and after a while, they simply disconnect the line.
It "turns the guns" on them and they realize they need to create another phone number to keep the scam going.
 If enough people do this and simply bombard the jerks with crazy calls, they will eventually realize that it don't pay and will quit. At least that's what I've seen by doing so.

 Also, I spoke with a detective in Spokane by email. He told me that all law enforcement is very aware of this problem. The difficulty they are having in tracking these people down is that the numbers are computer generated. The scammers can re-create new numbers as they need them. It's also very difficult to trace. Hence, the magnitude of this scam continues.

Call & leave messages that we owe IRS a large sum of money & we are being sued. SCAM

Say call department immediately but have no name or reason. Super annoying

This guy called my 14 year old daughter looking for my mother her grandmother saying this was a final notice for IRS lawsuit.  I called him back and gave him her number and then I begin to think this didn't sound right that's when I found this.  I am going to tell my mom to block this number.

We keep getting these calls as well, a couple of times a day.  They also use 360-807-5515.