Are you on AT&T, and is the phone you are using an AT&T phone or an unlocked phone?
If you are on AT&T, and you can't get internet to work with an AT&T phone, try going online and selecting the correct phone model, then change your plan to the media max 19.99 plan. It's the same as the iPhone plan, just for a regular phone. (Granted, the iPhone plan SHOULD work in a regular phone, but if you still have issues after that then at least tech support knows what phone you are on.)
If you are using an unlocked phone either google online or call 611 (customer service) for the correct internet settings, which you often need to input for your carrier if a phone is unlocked.