This is definitely a scam. (One very dangerous is to call back) I received many times, sometimes several times a day. The message left was "This call is from IRS, the IRS agent file a lawsuit against you, please call back on 360-205-7066, they are waiting for your phone call." These kinds of scam already happened all over in the Asia countries for the past six or seven years. Recently, start to move to west countries. How to avoid these kinds scam? First, NEVER CALL BACK. NEVER CALL BACK. NEVER CALL BACK! (when you call back, they can reroute your call to a fake IRS phone, and ask you to pay the bill electronically. They can change their caller ID to any number, they can reroute your call to any number. Usually they work as a team, can be from 10 to 50, or even more than 100 people, and they call from third world countries, like Kenya, middle east countries.) Second, if the real IRS would like to contact you, they will mail you by formal document letter professionally, with very clear IRS department person name with job position, contact address, phone number, and case number.