Mine rang once also - however, I read about a scam where people hit call back and it goes to an offshore account that then bills you hundreds of dollars for "services". Basic rule, if was important, the would leave a message.
Got a call from this number this morning. Rang once and hung up. After reading this I decided to call them back private until I got to an actual person. Told them to F-off with their scam and to suck on my sweaty unwashed balls and called him a few racial slurs as well. Got him pretty mad since he started yelling back "WELL F-YOU A-HOLE!", then he hung up. Any place that isnt a scam wouldn't respond like that and would just hang up if the person they are talking to becomes abusive. I'm going to call them back a few more times and give them a bunch of invalid credit card numbers to waste their time.