No, really, that doesn't work. If someone is trying to run charges against your card using your card number, the company will terminate that number and reissue. They know it's a fraudulent transaction, they block it, they still cancel and reissue. Had this happen this spring. I absolutely always call and tell the card company my dates, and I only take one card with me when I travel, and it's one I don't use except when I'm traveling. And I still end up with the security dept. calling me to tell me that they think there are fraudulent transactions being entered and they're reissuing.