The “Not registered on network” error is a common issue for the Samsung Galaxy owners when you have a null IMEI number or when the IMEI number has been changed. For those that have seen the error message and got grey hairs that something was probably wrong with their Galaxy smartphone, there is no need to panic.
Below is a guide that can help fix and repair a null IMEI number and make the “not registered on network’’ bug disappear. We also suggest that you use the free IMEI checker  just to make sure nothing is seriously awry with your Galaxy smartphone.
Below are ways you can use to terminate a null IMEI on basically all Android smartphones. Note that this also repairs the unknown baseband.
How to restore your Galaxy’s null IMEI and fix the Not Registered on Network error
- Power ON your Samsung Galaxy smartphone
- Open on the Dialer app and type in (*#06#) to display your phones IMEI number. If a “Null IMEI” message appears, then you will be required to change the settings to fix the “No Signal” or “Not registered on network” error.
- Type in (*#197328640#) or (*#*#197328640#*#*) on the dialer pad
- Your Galaxy smartphone will now switch to Command mode, then select on “Common”
- Now press on “Option 1” (Field Test Mode), if FTM is ON, switch it “OFF”
- This changes and restores the nulled IMEI number. It is important to press on the “Menu” button before leaving the Command page for this to be put to effect.
- Press on Key input then enter option 2.
- This switches the FTM OFF
- Dislodge the battery and remove the SIM card for around 2 minutes
- Put the battery back inside the Samsung Galaxy. Do not insert the SIM card
- Input (*#197328640#) on the dialer pad
- Hit on the Debug Screen
- Hit on phone control
- Press on Nas Control
- Press RRC (HSDPA)
- To fix “not registered on network” or Null IMEI error, press on RRC revision
- Power OFF your Samsung Galaxy smartphone and then reinsert your SIM card