Just a beep and a hang up. I thought it was a fax machine trying to connect. So I googled the company name that pops up on the caller ID "Sixtel, LLC" and found that this was just a nuisance call. They keep calling several times throughout the day and it seems to be getting more and more frequent. I am on a business phone and this is a waste of my time to have to keep answering a call when there is never anyone on the line.
If you call back, it says "we're calling to ask about your recent health insurance inquiry." Then it gives you the option to be removed from their calling list! (By the way, the last time I was looking into health insurance was 2 years ago...not exactly recent)