Select Menu > Settings > Security settings > Security level. Type in your security code, and select OK.

The default security code is 12345. To change your security code, select Menu > Settings > Security settings > Change access codes. Select Phone, and the phone requests the security code whenever a new SIM card is inserted into the phone. Select Memory, and the phone requests the security code when SIM card memory is selected and you want to change the memory in use.Keep the security code secret and in a safe place separate from your phone. If you forget the security code and cannot recover it, or if you type in the wrong code too many times, your phone will require service. Additional charges may apply, and the personal data on your phone may be deleted. For more info, contact Nokia Care.