The call comes from San Rafael, California they leave a message implying that the IRS is filling a law suit agains you and to call asap at this number 415-991-9389. Never answer or return this calls its a scam. IRS never calls it only sends legal responses by mail. If you are uneasy and worried about anything concerning any IRS matter you can always go to their website irs.gov or get leagal assistance from a certified lawyer.