How To Backup/Restore EFS Partition (IMEI) For Samsung Galaxy S3

Some users while installing a custom ROM, downgrade recovery or unlocking bootloader might lose the IMEI of   there devices and this will lead to losing network
This Guide will help you to make a backup of  the EFS partition for your galaxy S3
And if one day you lost/changed your device's IMEI or become NULL NULL, with this backup you will be able to restore it easily without any problem.

Requirements :
Rooted Samsung galaxy S3
Installed "KTool" app in your device (Link below)

Backing up instructions :
1- Open "KTool" app and accept the root permission

2- Press on "Backup EFS to /sdcard/efs.img"

(if you want press "yes" to verify the backup files)
3- Open "My files" then sdcard (you will find the backed up files)

Save the two files to your computer or upload it to the cloud
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Restoring instructions : (ONLY IF YOU LOST THE IMEI)
1- Copy "efs.img" and "efs.tar.gz" files to the internal storage
2- Open "KTool" app and accept the root permission
3- Choose "Restore EFS from backup (DANGEROUS!)"
4- Tap on "Restore IMG"

after it finished restart you device

YT Video link : http://www.youtube.com/watch?v=gf8JZSYbnkw

Notes :
~ This process will not help if you didn't have a backup
~ The backup will be saved in the internal storage as "efs.img" and "efs.tar.gz"
~ KTool work only on Samsung galaxy S2/Note/Nexus/S3 (International I9300 - *NOT* US variants)
~ NEVER RESTORE IF YOU ALREADY DIDN'T LOST THE IMEI
~ I am not responsible if something bad happened to your device (use this AT YOUR OWN RISK)

Downloads :
KTool app http://goo.gl/gcu66