Google’s Project Fi cellular network gained a coverage boost with Wednesday’s announcement of a third mobile partner in U.S. Cellular, currently the fifth-largest network in the United States. U.S. Cellular adds a second CDMA network to Google’s fledgling carrier service (Sprint being the first one, while Fi also uses T-Mobile’s GSM network).
To recap how Project Fi works, it’s a VOIP/data network that automatically switches your Nexus 6, 6P or 5X to the best available data coverage, be it a nearby open WiFi network, T-Mobile, Sprint (or now U.S. Cellular). Voice calls are VOIP (Voice Over Internet Protocol) handled by Google Voice and standard SMS/MMS texting is supported. Most coverage areas (especially in urban settings) are serviced by all three mobile providers and when no free, open WiFi hotspots are available, Fi automatically sets your phone to whichever mobile operator has the best signal in any given spot at any given moment. Below you can see Project Fi’s existing coverage map and U.S. Cellular’s coverage for comparison.
If you own a Nexus 6, 6P or 5X you can make the switch to Project Fi right now by simply going to fi.google.com and requesting a Project Fi sim card, or you can get a good deal on a 5X ($199 for the 16GB model) or a 6P ($499 for the 32GB model). The addition of U.S. Cellular will no doubt make the offers even more enticing.Source: Official Android Blog