Project Fi Google’s recently announced wireless cellular service, is a program to deliver a fast, easy wireless experience in close partnership with leading carriers, hardware makers, and Google users. As networks change in quality as you move around, Project Fi uses new technology to intelligently connect to the fastest network whether it's Wi-Fi or one of the partner LTE networks.
In addition to the technical reasons, what makes Project Fi appealing is that user will receive credit for any unused data at the end of the month. So, for example, if you pay $30 for 3 GB but only use half of that, you’ll receive $15 back.
Another first for Google and indicative of things to come.