Typically when you sign up for a phone carrier, you're just getting service from one network. That's not the case with Google Fi (formerly Project Fi), which lets your phone actively switch between T-Mobile, Sprint and US Cellular. It's a big selling point for the service, and when you add in Wi-Fi calling and texting, it's quite the network juggling act.
After using Google Fi for some time, though, it turns out the regular switching between networks isn't all that confusing after all.
Switching between T-Mobile, Sprint, and US Cellular
Google Fi, when paired with a compatible phone like the Pixel 3, is set up to intelligently choose between T-Mobile, Sprint, and US Cellular's networks depending on which one is offering a better signal at the time. We don't really know how Google's deals have been worked out with each carrier or how the phone determines when to choose one network over another — and with a Fi SIM or eSIM in your phone, the "Cellular network settings" go blank, aside from a single toggle to enable mobile data and data roaming (which you wouldn't ever worry about turning off anyway). That means you don't have any control over which network your phone uses, but it's not actually as scary as it first seems.
In our time using the service all around the U.S., we've seen the phone latch onto T-Mobile primarily, typically only moving to Sprint in some rural areas where T-Mobile has weak or no LTE signal to offer. As Sprint has improved its average speeds and reliability over the past couple of years, we've started to see it used more and more as well. You're only likely to see US Cellular in the regions where it actually runs its own network.
The most interesting thing to note is how seamless the transition is between networks when the phone decides to switch. There isn't actually any indication on the phone when it switches, and no matter which network you're on, the phone will always display "Fi Network" in the status bar. If you really want to keep track of the network switching, though, you can download an app like SignalCheck. Most importantly, there isn't any change in the experience that indicates a switch had been made — no delays, no cutoffs, and no slow data.
While there are technically ways to explicitly choose just one network over the others, we wouldn't actually recommend that. Considering how smooth the transition is between networks, there's little reason to bother with manually switching or sticking with one — and it really defeats the purpose of paying what are still above-average per-gigabyte data rates to get access to all three networks.
The one clear downside of this network switching is the lack of simultaneous voice and data when your phone is on the Sprint network — meaning if you receive a call, you won't be able to use data at the same time if your phone happens to be connected to Sprint. This really is the only reason to try and force the phone to one network or another ... and the only annoyance of this opaque network switching.
All in all, it's a win. Google Fi manages all three networks really well, to the point where you can't perceive the changes, and the parts of the country where the networks don't overlap simply give you more room with data than you'd get by going with a single network.
Then you add in Wi-Fi
Plain old carrier networks aren't the only story here — there's also a significant part of the Google Fi experience that leans on Wi-Fi (hence the name). The first part of this is built-in Wi-Fi calling and texting, which can utilize your current Wi-Fi connection instead of the cellular networks. This only works when your Wi-Fi connection is deemed fast enough for calls (it doesn't require much speed), but it'll seamlessly drop to the cellular network if necessary without any interruption. This works in the built-in Phone dialer and Google Messenger apps.
This means you can call and text no matter where you are, even when out of cellular range, but perhaps the nicest feature about this Wi-Fi calling and texting is that it doesn't require any intervention or settings manipulation on your part. Simply pick up the phone and call or text, and it'll go out over whatever network will handle it best. And because your "Fi Basics" charge covers unlimited talk and texts, you don't have to worry about which way it's routed.
The other part of the Wi-Fi story is the so-called "Wi-Fi assistant" that automatically connects you to open Wi-Fi as you move about — assuming you have a Pixel. If you choose to keep your Wi-Fi turned on at all times and let the Wi-Fi assistant scan for networks (which is enabled by default), your phone will automatically connect to any completely open Wi-Fi network that it finds and is "verified as fast and reliable" by Google.
It will only connect to networks that are completely open — that is, no password, splash page, "click here to connect," or "watch this advertisement to connect" getting in the way. While at first you may think there are plenty of open networks around you, many of them actually require this extra step of a splash page or some kind of authentication that'll keep your Fi phone from connecting. But because you don't have to actively manage it, it's always nice when you look down and see your phone has been saving mobile data by hopping on a coffee shop's free Wi-Fi.
When your phone does find a completely open Wi-Fi network that it can connect to, it'll connect and you'll be using it for data instead of the cellular network. You'll also automatically be connected to a Google VPN service, which is completely free and tunnels your connection past the inherently insecure Wi-Fi network through Google's servers to hit the outside Internet. This is good for your own security, and also helps you maintain a consistent data connection. When the connection degrades or you start to leave the area, your phone will hand off back to the cellular network — including any ongoing calls.
Living the multiple network life
So long as you don't try to tinker much and simply trust what the phone and service can do automatically, you'll be satisfied with the network switching and automatic Wi-Fi access in Google Fi. Having open access to T-Mobile, Sprint, and US Cellular means there are few places where you'll be left without a mobile data connection. And in areas with bad speeds from one of the three carriers, there's a good chance the other two can pick up the slack instead. Network redundancy is always a good thing.
In places where you have access to Wi-Fi — be it a known network or an open one out in public — the built-in Wi-Fi calling and texting features, along with the help of the Wi-Fi assistant, will let you keep using your phone in areas with bad mobile networks or just to save you a few dollars a month in data usage. It's simple, and for the most part it works — it's a truly useful part of the Google Fi experience.
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Andrew was an Executive Editor, U.S. at Android Central between 2012 and 2020.