You can either call customer service and have data blocked, but sometimes they will do it wrong and block picture/video messages as well. How i did it was that I logged into myverizon on my home computer and there is an option on the bottom to "change features" under the section labeled plan, click on that. Then on the right side of the screen there is link under the "related actions" section that says "Manage Service Blocks" click that. Finally select "block all data features" and click update. Your done and can now use your phone without fearing data charges and yes you can still use WIFI.