Its not. The caller ID is deceptive in the fact that this is a survey company using the same initials as SS.  There are many other threads here with this same survey company and initials.

They called today. No message.
CID says "SSI". Why the social security people might be calling, no idea. So I'm guessing it's not the "real" SSI people.

Have called me twice now, same time for two nights. They leave no message.