Everyone knows the names of the major wireless carriers in the US – AT&T, T-Mobile and Verizon – but there are many others as well. Google Fi Wireless is one of the more popular alternatives to the Big Three, but you may be wondering how it actually works. We’re letting you in on Google’s secrets.

What is Google Fi?

If you’re wondering what network Google Fi uses, you probably already know that it’s not a typical wireless carrier. It’s what’s called a “mobile virtual network operator,” or MVNO for short. Think of it like a wireless company that rents space on the networks of larger carriers like Verizon and AT&T. It’s a great deal for everyone involved: the big carriers get extra money, and Google Fi can offer its service without having to build its own towers. Other popular MVNOs in the U.S. include Mint Mobile, Tello, Ting, and Visible.

Which network does Google Fi use?

Google Fi has actually used multiple network providers over the years. It started in 2015 as “Project Fi” and used three different providers: T-Mobile, Sprint, and US Cellular. Its most important feature was the ability to switch between these providers to find the best signal, but this only worked on a few phones. Later, Fi worked on more phones, and when T-Mobile bought Sprint, this switching feature wasn’t as important.

Currently, Google Fi only uses T-Mobile’s network (US Cellular stopped working with them in 2023), so they have good coverage where T-Mobile is strong. This is great because T-Mobile has one of the best networks in the US, which is why many other MVNOs use it as well. Google Fi customers can get 5G in several flavors: mmWave, low band, and mid-band.

What about roaming?

One of the downsides of MVNOs is coverage when roaming outside your country. Google Fi roaming is (mostly) simple. When you travel outside the US, Canada, and Mexico, your phone will automatically connect to a compatible network. You can call, text, and use data just like you would at home. No complicated settings or manual switches required.

If you have Google Fi’s Flexible or Unlimited Plus plans, your data rates are exactly the same domestically and internationally. Texting is still free, but calls cost $0.20 per minute. Google Fi’s third plan, Simply Unlimited, doesn’t include international calling, texting, or data. For more information on the plans, see our full Google Fi explanation.

Because Google Fi uses T-Mobile’s network, you get good coverage in many places. You have the option to pay only for the data you use, which is great if you don’t need a lot of it. If you like having control over your phone plan and live in an area with good T-Mobile coverage, Google Fi is a good option.