You can unlock your Nokia 6300 using mobile unlock code..
It is on the website http://www.mobileunlockguide.com/mobile-phone/16854/nokia-6300/
The instructions are as follows:
Warning: Do not enter
any wrong unlock unlock codes on your Nokia 6300 mobile phones. If you
enter over a certain amount of wrong unlock codes on your mobile phone,
your phone may get hard locked and sometimes become unusable.
1 - Switch on your Nokia 6300 mobile phone without
any sim card.
2 - Don't bother as to what is displayed on your Nokia 6300 mobile phone.
3 - Compose #pw+CODE+1#
4 - The Nokia 6300 mobile phone would then display the message "SIM Restriction Off" and will be unlocked!
The letter p
appears if you press the button star(*) three times quickly
The letter w
appears if you press the button star(*) four times quickly
The symbol +
appears if you press the button star(*) two times quickly
you need to enter is the unique unlock code for your Nokia 6300 mobile phoneEach Nokia 6300 mobile phone has an unique unlock code. You can buy the unique unlock code for your Nokia 6300 mobile phone at www.mobileunlocksolutions.com.