The best line of defense against this type of identity theft is never to provide this type of information to a caller over the phone. Legitimate businesses and governmental agencies will never call a citizen and ask for this type of information over the phone.
If you make a phone call to a business that you are not particularly familiar with, particularly if you are calling in response to an advertisement you receive, be very cautious about providing any personal or financial information over the phone in such a situation.
When it comes to providing personal and financial information over the phone, be 100% certain that you are communicating with a reputable business on the other end of the line. This includes your bank or the company that provides you with a credit card. By dialing these businesses direct, you will be certain that you are dealing with a bona fide establishment and that you are conveying your personal and financial information through appropriate channels.