This is taken from my SGS II official thread which is applicable to the Galaxy NOTE. ALWAYS have your phone IMEI backup just in case ir t goes missing during flashing. It will save you a trip going to service center
How do I backup my phone IMEI in case it gets missing during flash process ?Check to see if your IMEI number is still intact by dialling *#06#
efs doesn't get backed up or restored by nandroidWhy the /efs folder?This is a very sensitive system folder that contains Phone-specific information such as the IMEI (encrypted in the nv_data.bin), wireless devices MAC addresses, product code (also in the nv_data.bin), and much more. Often users trying to change product codes or trying to unlock the mobile will end up corrupting data in this location.
Why back it up?Well, let’s resume it saying that backing-up this little folder will keep you away from Samsung service centres.
Easiest : Use HellCatDroid tool - just download and install kTool.apk file. Launch the app and select your choice :
http://f.lui.li/get_99_f13d.htmlOR you can use
Through TERMINAL commands What you will need:
Rooted SGS NOTE to get permissions as a SU (Super User) and perform the backup
Terminal Emulator by Jack Palevich (available from the market) <-Terminal Emulator or use ADB which is included in the SDK Development Tools
The standard prompt of terminal (adb) is a $ sign. Once you enter “SU” it will become a # Sign.
***NOTE: Make sure to keep an eye on the screen of your SGS II during this process, because it may request SU permissions [currently doesn't on CF-root]; else, you will get an error (just if it’s the first time). In Terminal Emulator you will need to reset the app after granting permissions cause it usually freezes***
*Remember: to use ADB you need to enable USB DEBUGGING under Applications/Development in your SGS II.
su
mkdir /sdcard/efs
busybox tar zcvf /sdcard/efs/efs-backup.tar.gz /efs
cat /dev/block/mmcblk0p1 > /sdcard/efs/efs_dev-block-mmcblk0p1.img
Close terminal emulator, then transfer to your pc.
RESTORING : Restoring efs backup (It helped when the phone is not working and imei is blank):
put your efs-backup.tar.gz in sdcard then in adb shell
su
umount /efs
mke2fs /dev/block/mmcblk0p1
mount -w -t ext4 /dev/block/mmcblk0p1 /efs
busybox tar zxvf /sdcard/efs-backup.tar.gz -C /
Reference :
http://forum.xda-developers.com/showthread.php?t=1068193Is this really necessary to do. What happen if I lost my iMEI and i did not do a backup ?If you lose your IMEI means : your phone cannot detect your sim card at all, you cannot make and receive calls, you cannot have internet access. If you go to Settings/About Phone/Status/IMEI - you will see a blank ou stated UNKNOWN.
You can try to recover it by either flashing a stock official rom ( full set PDA, PHONE, CSC) or try flash just the modem file. If these failed, your only choice is to send to Service Center to rebuild your rom
The chance of losing the IMEI is very low but if you are a frequent flasher of roms, kernels, modem etc it might happen; these I called accidents. So better backup. Using the app I proposed just takes 1 SECOND. Restoring it another 1 second. Better be safe , preventive than sorry later. Since it is so easy, just do it. Accidents can happen without you knowing and no approval is needed from you to happen. When it happen, don't ask "WHY ME ?"
If you are flashing those HP, Motorola, CSL phones the chance losing your IMEI is very, very high
The XDA forum of Galaxy NOTE has another method - more tedious , need to do it through your PC:http://forum.xda-developers.com/showthread.php?t=1325369