They just called from this number and are stating that the IRS is filing a lawsuit against you and you need to call them back at the number. Do not call. I repeat do not call!!! If the IRS is suing you or needs to get a hold of you they will mail you something and they do not give out their "direct line." They have a 800 number you call back not a direct line.
The IRS has a processing center where mailed-in returns are handled, and they have a walk-in office (appointment times have to be made) in a strip mall at the Rundberg intersection with Interstate 35. They might have another office elsewhere in Austin, but I have not looked for it. In 2010 the IRS had an office on Research Boulevard (US Highway 183) and Joe Stack flew his airplane into that building. https://en.wikipedia.org/wiki/2010_Austin_suicide_attack
Congressional hearing:
http://www.nbcnews.com/business/taxes/tax-imp ... hearing-n341906
Canadian tax payers should click on the "Canadian_Info" link, below:
Canadian_InfoSeveral links, describing Canadian tax scams: