Google Fi v20 hints at using dual SIMs to speed up network switching

Google Fi v20 hints at using dual SIMs to speed up network switching

If you’re not familiar with Google Fi, it’s Google’s own MVNO carrier. While most MVNOs rely on the network of one larger carrier, Google Fi is different in that is uses three: Sprint, T-Mobile, and U.S. Cellular. Compatible phones are able to intelligently switch between those networks depending on coverage. The Google Fi v20 APK hints at a new way for Google Fi to do network switching.

An APK teardown can often predict features that may arrive in a future update of an application, but it is possible that any of the features we mention here may not make it in a future release. This is because these features are currently unimplemented in the live build and may be pulled at any time by the developers in a future build.


Phones that are “Designed for Fi” can do network switching through eSIM or a traditional SIM card. Fi can sometimes be slow to switch networks and users often complain about. In fact, there are 3rd-party apps that allow you to force the network to switch. Google Fi v20 hints at using dual SIMs to speed up that switching process, and it could potentially be used to bring network switching to more devices.

<string name="card_configure_starburst_activate">Maximize networks</string>\n<string name="card_configure_starburst_init_description">"Unlock faster network switching and more reliable connections by having Fi use both of your phone's SIMs."</string>\n<string name="card_configure_starburst_init_title">Maximize your networks</string>\n<string name="disable_starburst_auto_switching">Disabling multisim auto switching</string>\n<string name="enable_starburst_auto_switching">Enabling multisim auto switching</string>\n<string name="enable_starburst_device_failed">Unable to maximize your coverage</string>\n<string name="enable_starburst_device_fragment_text">"Unlock faster network switching and a more reliable signal by having Fi use both of your phone's SIMs. Your phone will restart."</string>\n<string name="enable_starburst_device_fragment_title">Maximize your coverage</string>\n<string name="starburst_failed_body">"We'll try again in a few minutes."</string>\n<string name="starburst_failed_title">Unable to activate second SIM</string>\n<string name="starburst_feature_not_enabled">Multisim feature not enabled, cannot toggle auto switching.</string>\n<string name="starburst_in_progress_title">Maximizing your network connections…</string>\n<string name="starburst_success_body">"You now have even faster network switching. Both of your phone's SIMs are now using Google Fi."</string> <string name="starburst_success_title">Your 2 SIMs are active</string>

The strings above are from the Google Fi v20 APK. We can see in a few places Google mentions using both SIMs to “unlock faster network switching and more reliable signal.” Essentially, one SIM would be connected to one carrier and the other SIM would be connected to a different carrier. This would allow the phone to switch between them more easily.

It looks like the app will have an option to “Maximize networks.” It will then guide the user through the process of activating both SIMs. This could be an eSIM and a physical SIM or two physical SIMs. Once the setup is complete, your two SIMs will be active on Fi.

Phones such as the Pixel 3 and Pixel 4 have eSIM and Fi has traditionally not required a physical SIM on those devices. But now you could use eSIM and put the SIM card slot to good use to improve your connection. Some phones have dual SIM slots and it’s possible they could use two Google Fi SIM cards to get network switching. We’ll have to wait and see how Google uses this feature.

Thanks to PNF Software for providing us a license to use JEB Decompiler, a professional-grade reverse engineering tool for Android applications.

About author

Joe Fedewa
Joe Fedewa

Former Managing Editor at XDA-Developers. Lover of all things with displays.

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