I have had several such calls, all in English, spoken by someone who was not particular native to it. They always say they are calling from Microsoft sevice center and that my computer is at risk. Sometimes they are calling from an American phone number (don't know if they can fake that), sometimes from somewhere else in the world. I have asked if they know to which country they are calling, and they don't. I have also told them that I live in Norway, and if there is something wrong with my Pc so that I need to be told, why doesn't someone from microsoft.no call me in Norwegian. I never get any plausible explanation. The want me to click on certain keys on my computer, which I of course never do, so they haven't had much gain from me. And once I also was at my Mac and they maintained that they could 'see' into my computer. I have asked them about their telephone bill when they are calling around the world like this.
Last time someone of that sort said that my computer was at risk, I replied it is not, but it will soon be if they get their way with it