Crooks.  Called and asked for my SSN, birthplace, etc.

>> I called several hours later and it was disconnected. <<

True.
Scammers who do not pay their phone bills frequently are disconnected.

Why, oh why, would you follow the directions in an anonymous PHONE CALL, rather than an official, snailmail document, that contained appropriate identification to prove who sent it?

Called today asking me to send personal identification for all family members in household. Said it was about medicade and the insurance market. I called several hours later and it was disconnected.