A few years ago I had a Blackberry Curve on T-Mobile with WiFi calling. And it was awesome! The Blackberry would automatically connect to any available wifi in the area (home, work, nearby Starbucks, etc.) and route all of my calls through WiFi, which were free. It was like having my personal cell tower inside my house or work. When I would walk too far from the WiFi coverage, the Blackberry would seamlessly pull in the T-Mobile tower signal without dropping the call. Is this available on the Nexus S?