They left a message stating that they are the irs, and that they are filing a law suit. I called the number back and the line is busy. Why would the irs call me from Colorado?
The call you received is an overseas scam and not the IRS.
https://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
https://www.irs.gov/uac/IRS-Urges-Public-to-Stay-Alert-for-Scam-Phone-Calls
http://www.cnbc.com/2015/10/28/guess-what-thats-not-the-irs-calling.html