Phone Calls from Credit Card Companies

I just received a phonecall through my cellphone (Caller number: 7953889) supposedly from a Citibank representative asking to verify information about my card. I am very very careful with my financial information and even if it is rude, I immediately told the caller that I am not answering any of his questions and that Citibank can verify whatever information they need in another form. I heard so many stories of identity theft and it is really scary out there.

I wonder if these calls are, in fact, legitimate. I really feel wary about these calls that come from nowhere. Do these companies really call us through our cellular phone? Do you have any experience of this kind?