From what I can gather on a Google search, it seems to be some sort of an entry into a contest in order to win prizes. They call about once daily and never leave a message, so I just blocked the number.  Caller ID always states "Unknown".

I receive a message from this number daily and it is obnoxious! I blocked the number but it still leaves a voicemail. It sounds like one of those creepy breather calls. When I answer it, they want me to enter to win a contest. How do I stop them from leaving me a message?

2 calls within minutes of each other and just dead air when I answered.

This number calls my cell daily.   I have blocked the number but it still breaks through, which tells me that this is a spoofed number.  I contacted T--Mobile and their advice was to join the DoNotCall list.  Did that back in 2004 to no avail.  Scammers don't live by the rules.  Their technical support is a little behind the times and he said they were working on technology for stopping spoofed calls.