Here is the secret Samsung doesn't advertise: If you ever installed Google Messages (even briefly) or if it came pre-installed, it silently registers your number with Google’s Jibe servers. Samsung Messages cannot register simultaneously.
to manually deregister your phone number. This often clears the server-side block. Clear App Data Settings > Apps > Samsung Messages > Storage Clear Data samsung messages chat registration failed fixed
Look for "Carrier Services" and ensure it is up to date. Here is the secret Samsung doesn't advertise: If