The EFS partition on your Samsung Galaxy Note 5 stores critical information about your device — the IMEI number. If this partition is cleared by mistake or by purpose, the IMEI number of the device is lost, which results in unacceptability of your device on every carrier in the world.

IMEI number is unique to each mobile device and something you should really care about on your device. Specially, when chances of losing it are pretty high when you use Odin to flash a firmware (which we all do). Odin has a checkbox for “Clear EFS”, if you by mistake check it then Odin clears the EFS partition of the device and hence the IMEI number is lost.

Thankfully though, dr.ketan over at xda already has an app that can backup and restore IMEI (EFS) on your Galaxy Note 5. The app is available as paid on the Play Store, but  dr.ketan has also provided a free version of the app as a .apk file, you can grab at the download link below:

Download Galaxy Note 5 IMEI Backup app free version

Using the dr.ketan’s app you can easily take a backup of your Galaxy Note 5 IMEI number, however, the free version may not have the restore functionality. To restore IMEI number on Galaxy Note 5 you can run the following adb shell command.

dd if=path/to/efs-backup.img of=/dev/block/mmcblk0pX

└ Replace path/to/efs-backup.img with the location of EFS backup file on your device and X with the EFS partition number on your device.

via xda