How to Fix "Not Registered on Network"/Wrong IMEI for Galaxy S3/S4/Note2

This tutorial will learn you how to fix "not registered on network", wrong IMEI for :

Samsung galaxy S3 GT-I9300 model ONLY.
Samsung galaxy Note 2 GT-N7100 model ONLY.
Samsung galaxy S4 GT-I9500 model ONLY.
Samsung galaxy S4 GT-I9505 model ONLY.

Before starting :

Backup your important data first just in case of this process corrupt your data.
Download and install Samsung mobile driver (Skip this if you already have Samsung Kies) (Link below)
Download MODEM.tar.md5 file then unzip it only one time (Link below)
Download Odin3 then unzip it (Link below)Disable the antivirus software, Close Samsung Kies and disconnect any device connected to USB ports on your computer.

Flashing instructions :
1- Run "Odin3" as administrator, Click on PDA button and navigate to Modem.tar.md5 file that you extracted.
2 - Shut down your device and make sure your device is completely off
3 - Put your device into download mode by pressing and holding (Volume Down + Home + Power) buttons
4 - Press Volume up to continue

5 - Connect the device to your computer by USB cable and wait until you get a sign in Odin (ID:COM section) and "Added" in message box.
6 - Make sure re-partition is NOT SELECTED [Very important]

7- Click Start and wait a few seconds until you see "PASS!".

Notes :

Do not disconnect the cable or turn off the device while flashing
I am not responsible if something wrong happened to your device (use this AT YOUR OWN RISK)
Install Samsung Mobile Driver or Samsung Kies if you don't see a sign in Odin (Step 5)
This process takes maximum 1 minute
In some cases this won't fix the wrong IMEI or "not registered on network" message
If your device stuck in boot loop after downgrading, factory reset your device from recovery mode (Vol up+Home+Power)

Downloads :