If this number appears on your caller id, you are the subject of an IRS phishing scam. The 509 number, a Spokane area code, is explained by the spoofers as an artifact of their using a Washington D.C.-based call center at IRS headquarters. They will provide fake names and badge numbers and insist that your are being sued by the IRS for back taxes. Take names and and numbers and give then no information. Then file an attempted fraud report at TIGA.gov.