Goodness, I was annoyed when they called my home at 8AM and then read that some of you got the call at 5AM! I guess I need to put them on my blacklist so they never scare the pants off me that early.
Its a scammer using an auto-dialer. The auto-dialer makes several calls at one time, assuming that most won't be answered, They have some operators in the boiler room, but often not enough to speak to every call that gets answered.
The way the scam works, the person you speak to will tell you that your computer is infected with malware and offers to fix it for a fee. If you agree they will walk you through the steps of letting them into your computer to fix it. But there is no malware for them to remove. They plan to install malware. They will leave malware that sends them the user IDs and passwords for all of your on-line banking and shopping, which will let them spend all of your money. They will leave software that lets them use your computer to run Distributed Denial of Service attacks.