Project Fi

Project Fi is a program made by Google to deliver a fast, easy wireless experience in close partnership with leading carriers, hardware makers, and our users. 
==About==
===What is Project Fi?===
Google created new technology that puts you on the best available network automatically, whether that be WiFi or LTE from Sprint or T-Mobile. The service is able to automatically switch you between cellular and WiFi networks depending on which it deems is the faster connection. Project Fi also attaches your Fi phone number to your Gmail account, so that you can make and receive calls or text from almost anywhere, including computers and tablets.
===How much does it cost?===
Google is charging just $20 per month for the “Fi Basics” which includes unlimited domestic talk, text, international text, low-cost international calls, WiFi tethering, and coverage in 120+ countries. From there, you add on data at $10 per 1GB. So if you want 2GB of data per month, you will owe $20 for the data plus another $20 for the Fi Basics.
This Fi service differentiates itself from typical carriers because of the fact that Google only charges you for the data you use. So if you buy 2GB worth of data at $20, but only use 1.4GB, they will refund you $6 for the 600MB of data you didn’t use for use on your next month’s bill.
If you buy 2GB of data and go over, Google only charges you at the $10 per 1GB rate. Even if you only go over and use 350MB, they calculate that at the same rate, so you would be charged an extra $3.50.
There is no annual contract with Project Fi. There are no termination fees either.
===Coverage===
To check to see if you will be covered by Project Fi, you can click through to Google’s Project FI coverage map.
From what I can gather, as long as you are covered by Sprint and T-Mobile LTE, you should be eligible for Project Fi.
Project Fi is currently only available in the US.
===Carrier partners===
Google has partnered with Sprint and T-Mobile for Project Fi.
===WiFi networks, data security, WiFi calling===
Google’s Project Fi allows you to connect to more than a million free, WiFi hotspots that they have verified as “fast and reliable.” When connected, Google sends your data over a Virtual Private Network (VPN), so that no one else on the network knows what you are up to. Connecting to these networks does not require any action from you, meaning you connect automatically without having to punch in a password or watch an advertisement.
As for calls over WiFi, they work just like your normal calls over cellular. Also, if you start a call over WiFi, but switch to a cellular network that is determined to be a faster connection, your call continues without dropping. That’s part of the beauty of Project Fi.
===International use===
Project Fi has you covered when traveling internationally with support in over 120 countries. The full list of countries can be found here.
Data usage runs the same $10 per 1GB, but the speeds are reduced to 256kbps (3G).
If you want to text while traveling, texts are free as a part of the Fi Basics plan.
If you want to call, you are charged 20 cents per minute when connected via cellular, and the rate varies on WiFi, though you are only charged for outbound calls on WiFi.