It is quite possible that fraudsters will telephone you in an attempt to obtain your credit card details. They may, for example, claim to work for a software company and to have identified a virus on your PC. To "resolve" the issue, you are asked to provide your credit card details and install a ridiculously expensive program that will repair the damage.
MELANI, the Reporting and Analysis Centre for Information Assurance, warns about such telephone calls. As Microsoft never makes unannounced or unsolicited support calls, the callers are most likely fraudsters whose sole objective is to tamper with the PCs concerned or infect them with malware.