T-Mobile has in its latest smartphone, the Shadow, potentially changed the way we think of cell phone service. Rather than use standard cellular signal, which requires a vast network of booster towers, the Shadow will offer unlimited nationwide calling over Wi-Fi networks.

Designed for ease-of-use, the Shadow features a navigation wheel, slide-out 20-key QWERTY keypad with predictive text function, and a vibrant 1.6 inch screen.

Powered by Windows Mobile 6.1, it is the first ever Windows-based phone to support calling over Wi-Fi networks.

And since no phone would be complete without goodies, the Shadow also includes a built-in 2.0-megapixel camera to capture stills and video, Wi-Fi web browser to chat in real time, and multimedia capabilities for a top-screen way to share music.

The big selling point, however, is the Shadow's ability to offer standard mobile coverage at home and unlimited calling from Wi-Fi networks or T-Mobile Unlimited HotSpot Calling service.

For full specs, click here.