[link|https://fixyourandroid.com/fix/not-registered-on-network/|Not Registered on Network error] is associated with mobile carrier network you get when there is some conflict with mobile network reception or SIM card. any attempt to make a call will display a pop-up “Not registered on network”. This can be caused by a series of errors including poor reception, SIM card registration fails, No network access in your area, etc. The error can occur on any smartphone including Samsung and others.
* Restart the Android
* Turn Flight Mode on/off
* Toggle SIM off/on
* LTE/VoLTE Connection switching
* Remove SIM Card and Re-insert.
* Reset Network Settings
* Manual Network Mode
* Clear Android Cache
* Enter Service Mode (Samsung phone)
'''And finally, don’t forget to check with your network provider and check is the connection is active.'''