Verizon Wireless is the carrier for this number. Call up Verizon and tell them that one of their customers is using their services for illegal activity. Verizon MUST follow-up and investigate and block them and all those from CELLCO (a Verizon affiliate) from your number. They just did mine. Verizon will give you a song and dance how they can't go around monitoring their customers activities. You tell them that that these customers are conducting illegal activities and it is their responsibility to do something about it.
Like mentioned I won a "Bahamas Cruise" and all I have to do is complete a "Scientific Survey". I pressed 9 to be erased from the system. Hopefully that wasn't really a "hey this guy answers the phone, put him on the list of phone numbers we plan to sell". FYI I have a cell and don't give my number out very often. It is probably dialing random numbers.