Cell Phones,Prepaid Cell Phones,Cell Phone Plans - Verizon Wireless and check your online account you can click on view my bill and see a full pdf that explains your bill. when you look at your bill check for 1. equipment charges (things you billed to your acct when you upgraded), and 2. there is a place that shows data and voice charges.
If either shows then you have voice overage or data overage i.e. downloads, 411 calls, etc.
Hope this helps