How to back up your IMEI for Xiamoi Phones

Many people complain about their phone not able to get network after flashing a new rom. I have got some thing really useful that will ensure that people will not have this complain again, i.e Backing Up EFS for your phone. Always Remember it's better to be safe than be sorry later, so, just do the backup and save it some where safe. So that when you loose the IMEI of your phone accidently, you have a backup for it and can live in peace.

Question: What is EFS?
Answer: EFS stands for " Encrypted File System" , it encrypts the critial phone identification data like IMEI, MAC ADDRESS of the device and stores them in a EFS partition.

Question : Why do we loose our network connectivity once we flash a custom Rom?
Answer : When our phone is not able to find its IMEI number, it will not be able to connect onto a network. This generally happen if you have lost your EFS drive.

Question : Why do we loose EFS of our phone.
Answer : We can loose EFS if we flash wrong rom (something that is not made for your phone) like a custom rom. Every flasher sometime or the other has faced this issue in their life.

Question : What does EFS Backup Do ?
Answer : Backing Up EFS will make sure if ever you loosed your IMEI , You dont have to worry, and rather Fix your phone in minutes. Its a DIY.

Question : What are the files Backed up?
Answer : These are three (3) Partitions, which hold imei and Nv - data . These Partitions are MODEMST1, MODEMST2 and FSG .


Prerequisites:

You need to install Miflash, for the drivers (Miflash Setup link at end of post)
You need to enable usb debugging from developer options (go to about phone in setting and tap build version/ miui version 7 times to enable developer options in settings menu)
You need to have ADB fully setup
Your Device needs to have ROOT permissions (use forum search feature to seach rooting guide for specific device and rom version stable / dev)
You need to make sure the Adb drivers are installed well
You need to have a Windows Operating System or terminal Emulator on Phone with root access

***note- Miflash has inbuilt adb setup, and adb diver so, you can follow below guide to use the miflash default adb.
So, lets begin ...
Connect the phone to pc, open COMMAND PROMPT and browse to the Miflash installed directory.

Enter the below commands one by one (assuming miflash is installed in directory C:\Program Files (x86)\Xiaomi\MiPhone\)
cd/.
cd program files (x86)
cd xiaomi
cd Miphone
cd google
cd android

Now, you have reached the Default ADB Configured Folder


Next enter the following commands one by one:
adb devices
adb shell
su

Now, you got the Root access (allow any thing popping up phone regarding root permissions).
if you get a error like permission denied, KINDLY CHECK FOR YOUR ROOT ACCESS AND PERMISSION


Now, we are good to backup Mi2/2S, Mi3, Mi4

Enter the following commands one by one:
dd if=/dev/block/mmcblk0p12 of=/sdcard/mmcblk0p12
dd if=/dev/block/mmcblk0p13 of=/sdcard/mmcblk0p13
dd if=/dev/block/mmcblk0p16 of=/sdcard/mmcblk0p16

Now, the backup is being done. You can check the Internal Storage from your phone for the files named mmcblk0p12, p13 and p16. Copy these files and keep them safe.

Now , we good to continue for Redmi 1S and Redmi Note LTE (4G)
dd if=/dev/block/mmcblk0p16 of=/sdcard/mmcblk0p16
dd if=/dev/block/mmcblk0p17 of=/sdcard/mmcblk0p17
dd if=/dev/block/mmcblk0p20 of=/sdcard/mmcblk0p20

After the the backup is made, you can check the Internal Storage from your phone for the files named mmcblk0p16, p17and p20. Copy these files and keep them safe.

 
Links :Miflash latest v 2014.05.09= MiPhone20140509 - Download - 4shared