Nrfr

Nrfr is an Android app that changes the country code associated with your SIM card, without requiring root access. The country code is a piece of information the phone reads from the SIM to decide things like which carrier settings to apply and which regional features to unlock. Changing it can fix compatibility problems when using a foreign SIM card, resolve situations where a phone fails to recognize carrier settings correctly, or allow apps that check the SIM country to behave as if the phone is in a different region.

The tool does not modify the SIM card itself. Instead, it calls an internal Android system API called CarrierConfigLoader to change how the operating system interprets the SIM's information. This approach avoids any risk to the SIM card and does not depend on third-party frameworks like Magisk or Xposed. Changes take effect immediately without a restart and persist across reboots. The app includes a restore function to revert to the original country code at any time. Dual-SIM devices are supported, and each slot can be configured separately.

Because the app calls privileged system APIs, it needs elevated permissions that are granted through Shizuku, a tool that uses ADB (Android Debug Bridge) to provide those permissions without root. Setting up the whole system involves enabling USB debugging on the phone, connecting it to a computer, and running a desktop companion application that automates the installation of Shizuku and the Nrfr app itself.

The README describes several practical use cases in Chinese: fixing operator configuration mismatches during international roaming, correcting display of carrier names, and resolving regional restrictions in apps that read the SIM country code. The Apache 2.0 license applies to the project. The desktop companion tool is built with Go and React using a framework called Wails, while the Android app is written in Kotlin.