I did not answer. No message left.  I called back.  An indian type man answered.  Phone was breaking up.  He said he was calling from Microsoft (HA HA) and that my computer was infected.  I said this was a terrible connection and that he was a terrible liar.  I hung up.

Didn't answer but a voicemail was left. an automated message told me to call because because my "Microsoft Windows computer is infected and my personal files could be lost." almost 100% sure its a scam.

Just got the same message about my computer with Windows being infected and would be rendered obsolete if I didn't return their call. CID showed "Not Available". What was absolutely hilarious was the message ending with "If you are not a Windows customer, please ignore. Thanks".

I also received a voice message.  It is a total scam.

CRIMINAL HARASSMENT and FRAUD attempt by the same despicable characters that engineered or participated in the recent IRS harassment scam.  Same female voice, same broken English.  DNC registered victims should report such HARASSMENT calls to the FTC for future prosecution.
https://complaints.donotcall.gov/complaint/complaintcheck.aspx