Project Fi. It is Google’s MVNO (mobile virtual network operator), which I first and last wrote about in April 2015 in an article titled 'Google Fi - how might it fare in Australia' when it only worked with the Motorola-made Nexus 6 handset and you needed an invite to take part, although since that time, Google has added support for its Nexus 5X and Nexus 6P handsets too, as seen as this Project Fi FAQ.
Project Fi provides wireless phone and data services using Wi-Fi and cellular networks belonging to Sprint, T-Mobile, US Cellular, and Three UK.
Not only does the service work with the above telcos, but it also "works with more than 1 million open and free hotspots that Google has tested and verified as not just fast but reliable, and will then encrypt your connect once it is made".
The handover between LTE and Wi-Fi is promised to be seamless, for the best possible coverage.
You pay US$20 per month for the service to get "all the basics of talk, text, Wi-Fi tethering, and international coverage" which has now expanded to 135+ countries, along with a "flat $10 per GB for cellular data while in the US and abroad. 1GB is $10/month, 2GB is $20/month, 3GB is $30/month, and so on".
Part of the problem for Google has been, as it describes in an official blog post by Tyler Kugler, product manager, Project Fi, that "the data we have access to when travelling abroad often isn’t fast or affordable enough to let us do the tasks that matter most", which Kugler says "could be why only 20% of Americans opt to use their cellular data when traveling internationally, instead choosing to jump between Wi-Fi hotspots or scramble for a local SIM card".
Kugler says that Project Fi subscribers can now take advantage of the addition of the Three network in the UK ensuring that Google is "now able to deliver speeds 10-20X faster than before,’ with the price for data, even internationally, still ‘the same US $10/GB that you [pay] at home [in the US]".