How do I lock my SIM card?

To lock your SIM card, follow these steps:

1. From the main screen, press the OK key.
2. Using the navigation keys, go to the "Settings" icon. Then, press the OK key.
3. Go to "Privacy & Security."
4. Go to "SIM Security." Then, press the OK key.
5. "SIM PIN" will be highlighted. Press the OK key.
6. Go to "On." Then, press the OK key.
7. Use the dial pad to enter the default PIN 1111 or 1234. Then, press the key below "Done."
8. To change your SIM card PIN, go to "Change SIM PIN." Then, press the OK key.
9. Enter the current SIM card PIN. Then, press the DOWN navigation key.
10. Enter the new 4-digit PIN. Then, press the DOWN navigation key.
11. Enter the new PIN again to confirm. Then, press the key below "Done."