Solve Null IMEI Unknown baseband Not registered on network after downgrading Samsung Galaxy phones

Solve Null IMEI, Unknown baseband, Not registered on network after downgrading Samsung Galaxy Phones

Did you just downgrade your Samsung Galaxy device just to find out that you are now left with no network signal at all, Null IMEI and Unknown Baseband? You are not alone as this just happened to me as well. This tutorial will show you how to Solve Null IMEI Unknown baseband Not registered on network after downgrading Samsung Galaxy phones from Lollipop or any other ROM.
Android OS updates are an exciting treat as they come offering loads of new goodies like improved user experience, better resource management  for our older devices. While many of us will be in a hurry to grab the latest updates for their devices – as we should, it’s only a matter of time that some of us realize that not all is smooth with new Android updates. Many early firmware releases contain OS bugs while at other times users may find the newer OS to be a steep learning curve compared to the familiar OS interface they may have been used to. For these reasons, we sometimes find ourselves in dire necessity to downgrade our firmware from say Android 5 Lollipop to Kit Kat 4.4
On some Samsung devices, this downgrade process is not always without hiccups as many of us have come to learn in a pretty stifle way. With reference to Samsung’s newly updated EFS system on newer ROMs, there are some significant changes to the partitioning structure on these Galaxy devices. This means that unlike before, downgrading your Galaxy phone back to an older firmware might prove to be a nightmare once you have updated to newer firmware.

Cause for Null IMEI, Unknown Baseband on Samsung Galaxy devices after Downgrade

In most cases, Android kernels (firmware) have no issue switching between different modem versions but sometimes flashing older modems on newer Kernels and vice versa may prove problematic (Refer to Samsung new EFS system). The modem/baseband is the firmware part responsible for network connectivity on Android phones.
This may happen when you downgrade your Samsung phone from say Android 5 Lollipop to Android 4.4 Kit Kat, from Android 6.0 Marshmallow to Lollipop or from Kit Kat to 4.3 Jellybean. You can now see how downgrading your firmware back to an older firmware could spell trouble once on newer firmware which uses a relatively newer kernel.
Now that you have understood the cause for Null IMEI, Unknown baseband and not registered on network problem after downgrading your Samsung Galaxy device, I will now show you how to solve this problem in a few steps.
This repair tutorial will work across different Samsung Galaxy models including Samsung Galaxy S4, S3, S5, S6 and Samsung Galaxy Note 3, Note 4 and Note 5 series. You just need to work with your particular device ROM but the process is the same across all models.

Solve Null IMEI Unknown baseband Not registered on network after downgrading Samsung Galaxy Phones

For the purpose of this tutorial we will assume you downgraded your phone from Android 5xx Lollipop to Android 4.4xx Kit Kat. Whatever firmware you downgraded to, you will now need to download a higher and later firmware version than your current one (without network signal/IMEI problems)

  1. Download stock Android 4.4 kit Kat for your device from Sam mobile. (Skip to Step 3 Assuming you have already flashed Kit Kat firmware on your device)
  2. Flash the downloaded stock ROM in Odin.
  3. Now download latest stock Android 5.xx Lollipop preferably from the same region. ( It does not matter if you download 5.1 or 5.0.2 whichever is latest for your device)
  4. Extract the downloaded Lollipop file to the desktop using WinRAR.
  5. Again extract the ROM.tar file to get .bin file.
  6. Put your Galaxy device in download mode and connect it to PC using original USB cable.
  7. Open Odin 3.09 and using CP (Phone button in older Odin) load the extracted modem.bin file into Odin. Do not change Odin default settings. Flash the Modem.bin file to your phone by clicking on the START button.
  8. Once the process is complete with a ‘Green Pass’ message in Odin, disconnect and let the device boot up (First boot takes longer)
  9. You should now have your network working again, with original IMEI and the correct baseband showing. Check IMEI *#06# to confirm original IMEI has been restored.

Solve Null IMEI, Unknown baseband, Not registered on network after downgrading Samsung Galaxy Phones

EXPLANATION: Older ROMs use older Modems that sometimes won’t work on newer Kernels after upgrading. The solution is to grab a newer ROM, extract the modem.bin file, flash this modem into the current problematic ROM.

CAUTION: DO NOT try to repair the IMEI before trying this tutorial! The EFS folder is not damaged and the original IMEI data is still intact. It’s the baseband file that is not able to retrieve EFS data into memory.
If the flashing the modem.bin does restore the Baseband and Null IMEI, try reflashing again with “Auto-reboot” option in Odin unchecked. You may also try flashing a different modem.bin from another Lollipop ROM.
NOTE: The newer the Baseband/modem, the better the chance that it will stick. Most newer modems also tend to have better signal reception as well. To know which ROM is using a newer baseband, check the last 2 digits of the firmware code. A higher number will indicate how old the baseband is. E.g. XXUNFG1 is older than XXMSH6.
Using this method, I was able to fix my Galaxy S4 to Null IMEI, Unkown baseband and back to a full network signal bar.
I can only hope that this tutorial will be of great help to you and many other users looking to solve Null IMEI, Unknown Baseband, Not registered on network after downgrading Samsung Galaxy device from a newer operating system.
Found this helpful? Share! Comment below, and subscribe to us!

You may also Like:  How to Fix E: failed to mount /efs (invalid argument) in All Samsung Galaxy Phones.

Happy Geeking!


Charles Kamara
Follow Him!

Charles Kamara

Charles is a PC technician, tech blogger, infopreneur and an avid reader. Writes about tech that interests him most and more importantly to his audience, he offers solid technical experience in easy DIY tech repair guides. A sociable geek who loves to experiment with gadgets.
Charles Kamara
Follow Him!
  • Pablo Gomez

    Hey great post, …OK so I was messing with the service menu and somehow managed to wipe my serial number from my phone and now I’m not receiving any signal from my CDMA network Which uses verizon towers but when I pop in a GSM carrier it works fine…I knew I shouldn’t have messed with the service menu settings…any ideas?

    • Pablo Gomez

      By the way I have a VERIZON NOTE 4

    • Thanks Pablo. The device serial number should look like this: RV1D710MDAR. Check if you still have the original IMEI intact.

      • Pablo Gomez

        Thanks for responding… I used Odin to go back to stock rom and it helped with setting back the original settings since I’m receiving signal again …and I checked my imei and its showing correct as far as I know, except my s/n number is now 000000000 ….any ideas?

        • A temporary solution would be to write device serial with Xposed Framework (Use Serial Number Changer module) You might be able to restore the Note 4 CDMA reception. You will need to be rooted.

          • Pablo Gomez

            Thank you…i will try that and let you know the results

          • For Qualcomm Note 4 devices like Verizon Note 4 N910V you might be able to use QPST program to permanently restore to the original device s/n.
            Kindly let us know if you need more help