I've been getting phone calls from "(866) 831-7288" or 801-831-7288 over the last few weeks. They never leave a message.
Today I decided to call them back, and got a recorded message.
"Thank you for calling Web Site Pros, a full-service website marketing company for small companies."
Basically, someone sold my information to a marketing company.
Who sold them my information?
According to the recording, it could have been Discover Network, Vista Print, Card Service International, Authorize.net, Yahoo!, Intuit (makers of Quickbooks), etc.
In my case it was probably VistaPrint (I ordered some "free" business cards from them, and, of course, submitted my business number to them to include on my business card).
Now you know.