Wifi is built into some BlackBerry models to support Unlimited Mobile Access (UMA). If your carrier does not support UMA, you can still use Wifi with your Browser.
Options / Advanced Options / Browser. Set the default to Hotspot Browser.
When you are in range, you will be able to Browse the Internet at very fast speeds. If you move out of range, you will get page load failures, not a switch over to the expensive carrier network.
