Sun, Apr 26, 2015 Google has announced that it will be offering Google Fi, a cross-carrier MVNO cell plan available only to unlocked Nexus 6 devices. The pricing scheme and cross-carrier network is a unique offering when compared to other popular MVNOs. Carrier-Switching The cell service will be the first to offer carrier switching between Sprint and T-Mobile. They will also offer calling over WiFi, similar to services offered by T-Mobile. This would give Fi users an advantage over other MVNOs in that their device would automatically find and switch to use the best available connection across Sprint, T-Mobile, and WiFi.