IT IS A SCAM. First the caller said that he was from Dell and he read our Dell ID number to us. Then he said he was from Microsoft. He called a total of 7 times. We told him we knew he was a scam, and that we were reporting him. He became irate and threatened us and said "I will blow you up' and screw up your computer so (we) could not use it for 6 months. We reported to local police and also pulled out and disconnected our router and changed our hard drive. We also put Life Lock in place. There had been a breach in our info when we checked on Life Lock (well worth the money to get life lock). We changed all our pass codes etc....... We also called Comcast to see if we could get a new ISP #. They said that every time you turn off the computer and disconnect from router, the ISP changes. Good to know.