The caller had a thick foreign accent, identified themselves as a representative of the victim's credit card company, and was able to provide the potential victim with the first four numbers of the victim's credit card. Then the victim was asked to provide the rest of the card's numbers.
The potential victim did the correct thing at that point and simply disconnected the call without providing any more information and thus did not suffer any loss. The first several digits of a credit card are known as IINs (Issuer Identification Numbers) and are not unique to individual credit accounts, thus those numbers could be provided by a scammer in an attempt to trick a victim into believing the caller is an actual company representative. So, as a reminder, never provide personal information on the telephone after receiving a call, even from a source that might identify itself as a company you do business with.
A legitimate business will be able to provide you with a call back number and other means so that you can verify their credibility. When in doubt, simply hang