This is a callback number given in a robbocall from 276-477-5822:
"We have been trying to reach you. This call is officially a final notice from IRS. Internal Revenue Service. The reason of this call is to inform you that IRS is filing lawsuit against you. To get more information about this case file please call immediately on our department number 253-336-5321. I repeat 253-336-5321. Thank you."