What will it gain you? Don't do it-never call back numbers you do not know. You get no extra bonus points for knowing what/who they are (you probably won't find out anything anyway and just waste your time). Curiosity KO'd the cat.
I got a call it went to voice mail from a Kellie the # 6099862519 said that are the IRS when I call back it's busy or a wrong # wanting to talk my tax return