It's a phishing scam.  Do NOT provide them with any sensitive information!

A recorded message from [Unintelligible] Credit Union announced that my VISA card had been suspended.

The recorded message then asked for my 16-digit credit card number, followed by the pound sign, to revalidate the card.

I entered "1234567891234567" as a dummy number to see if maybe I'd get a human being on the line, but no joy, so I hung up.