I received a call from this number and it sounded very legitimate, but I hung up and instead called my wireless company and asked if it was their number. They looked into it and said it wasn't and not to send any payment. This number appears to be a scam.
It's Verizon Wireless. They use unidentifiable cell numbers sometimes in hopes that you'll pick up thinking that it's someone call from a cell phone and not a bill collector. Never pick up a number you don't recognize.