How to Downgrade From Baseband
- 1). Tap the "Settings" application, or app, on your iPhone. This brings up a menu for the settings and tools.
- 2). Touch the "Network" option. This opens up another submenu on your phone.
- 3). Unselect the data plan you have. For example, if you have 3G, tap the checkmark next to it. This will revert your iPhone back to the 2G network.
- 4). Press the "Home" button to return to the main screen. Test the new connection on your mobile browser.
Source...