As far as I understand it (my dad worked for the labor union for decades) it's absolutely illegal to use SSN for anything other than taxes - a law that is regul

As far as I understand it (my dad worked for the labor union for decades) it's absolutely illegal to use SSN for anything other than taxes - a law that is regularly broken in this country. If some recruiter asked me for my SSN over the phone I'd laugh at him and if he pushed the issue, I'd walk away or try to get hold of his boss depending on my mood. Certainly a recruiter has no business knowing your SSN!