Oftentimes when you enter an area with a strong Wi-Fi connection in it, such as a hotel or university, you will see that internet connection immediately over power your iPhone's 3G network connection. You will then not have the ability to just connect to the internet through different applications just with the 3G network. You will then have to connect to that said network, and the username and password may be required before you can actually go online. If you have that username and password, it is fairly easy to connect to the Wi-Fi option on your iPhone.