I am a Certified Identity Risk Management Specialist and this call is a Scam and they are either Phishing or Pharming for your personal information. Do not under any circumstances give them access to your computer, go to any site that they might send you to, provide them with credit or debit card information, or provide them with any personal information. They are not associated with Microsoft the manufacturer of windows. In fact a VP of Marketing for Microsoft in Austria said that Microsoft never contacts their customers, unless the customer called Microsoft for support, and in that case the customer is given a reference number to avoid any complications from someone calling and falsely identifying themselves a representative of Microsoft.
Received a call from this number - 240-845-6623. Man asked what are you downloading and to stop downloading right away. He said he was with Windows and again to stop downloading with urgency in his voice. This call came in on my boss's cell number here in Arizona and told him to speak to me. That maybe I was downloading something. When he gave me the phone and I asked how I could help him he asked to stop downloading. Then he paused and asked if this was a home or business number. I said to him, you called us and gave name of business. He promptly hung up. He had heavy accent, could have been from India. He has not called back. The only thing I could find out about this number is that it is a land line and the carrier is XO communications.