Can I Use A iPhone Without Paying Service Fee?

Currently I'm using a LG Optimus V which used to have service from Virgin Mobile. I do not use the phone for making phone calls so I do not pay for service, I just use it for music and to send emails using Wi-Fi. I'm thinking of buying a Refurbished iPhone 4 and I need to know do Apple phones work the same way where I can just use it without paying for service, just as a mp3 player and something to browse the internet with wherever there's Wi-Fi.

Why not just buy an iPod touch if you don't plan to use the iPhone… As a phone?