The pin protects your SIM card from unauthorized use if your Samsung Galaxy S9 is stolen or you lose it.
If PIN use is enabled, the PIN must be entered when powering on the Samsung Galaxy S9. If you do not need this security feature, you can disable the Sim Pin as follows:
Remove Sim Pin - Instructions
1. Open Settings.
2. Select the menu item "Device Security" from.
3. Go to "Other Security Settings" and then "Configure Sim Lock".
4. Here you have to deactivate the option "Lock Sim Card".
5. Confirm the setting by entering your current pin.
You have now successfully deactivated the Sim Card Pin on your Samsung Galaxy S9.