Lock iPhone 12 on 3G network

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[Update] Jailbreaking on iOS 14.3 and below is now available. This article got an update here.

Thanks to the recent exploit on iOS 14.3 and below, now we can use Plankfilza, aka Filza built by brandonplank, to modify system files.

The Reasons

This tutorial is for you who have a way better 3G signal than 4G or don’t have a 5G network in your local area, whatsoever, who wants his 3G back.

3G option disappears when carriers enable 5G in iOS system profiles. So with the help of Filza, you can disable the 5G option, then your 3G switch will come back.

Let’s begin

1. You need to be on iOS 14.3 or below.
2. Install Plankfilza. You can check unc0ver.dev for ways to sideload apps. You can sideload Plankfilza with the same method of sideloading unc0ver. After installation, open plankfilza, and wait for its running exploitation.
3. Go to /var/mobile/Library/Carrier Bundles/ directory. Click the “i” button of the “Overlay” directory and change its owner’s permission to read and execute only. So system won’t be able to convert files under this directory back to their original versions.
4. Now enter the “Overlay” directory. Identify which profiles are your carriers’ that you want to modify. You can do so by clicking the .plist file and finding “carriers name” under the root dictionary.
5. Edit all .plist files you choose, change the value of “Show5GSwitch” to NO, then save these files.
6. Exit Plankfilza, reboot your device. (Exit Plankfilza may cause “soft” reboot, You may manually reboot once)
7. Finally, go to Cellular settings. The 3G option should be back.

I have tested it on my device: iPhone 12 mini on iOS14.3 RC(18C65) with China Unicom v45.2 and 3HK v45.0 working. And I’m sure this method will still work, after the actual jailbreak coming out.

Miss your 5G?

Want your lightning-fast 5G back? You can change the value of the “Show5GSwitch” back to YES, then reboot, or delete the whole “Overlay” folder, then reboot, let the system rebuild the directory for you.

Ref:「Tutorial」Enable awesome 2G / 3G / 4G Toggles by u/Imvbs on Reddit.

— Feb 18, 2021