They just called me and called back to find out who they are, I don't hear a ring and the timer in my phone is running, meaning there is a connection established, but no one answers.
Been getting this number calling me for the past few days. If you call it back blocked or unblocked and wait a few minutes you will hear a machine come on saying "Welcome to Hey Cosmo"
http://www.heycosmo.com/
This is just a new form of Spam. It’s only a matter of time before the FCC shuts it down. They start by providing a “free” service to people wanting to get their message out to a lot of friends, like twitter. They build their database of cell numbers and emails then sell them to companies for advertising purposes.