Got a call on my phone from an 800 number saying that there had been possible fradulent activity on my card (they did not specify which one) and they wanted to validate recent purchases. Given that the caller was automated and did not specify which company they were from, I was suspicious.  I was even more suspicious when I called back from a friend's phone and they wanted me to verify my phone number  before they would go further(!).

After I hung up, I called the companies whose credit services I used and checked: neither had called me. A little searching on the web suggested this number is used for phone phishing.