I don't think it's illegal to just have card numbers and socials. What if they just dropped in your lap from the sky? If I mail my CC and social to someone on a postcard, can I have them arrested the next day?
Some of the methods that you'd use to get that information are surely illegal (lying over the phone, stealing paperwork or data). Using them for anything is fraud and is definitely illegal. But I bet it's not illegal to call someone up and ask, provided that you don't lie or deceive or ever use them for anything.