If you are trying to unlock your pantech C810 and it gives you the following error:
This phone is only accepts SIMs from specific netowrks, and has been blocked. Contact you customer service center for the unlock block code.
Re-type new password:
Then you will need to reflash your phone before you can unlock it. Download and unzip this file. Follow the included instructions on how to flash your phone. Once it has been flashed, restart your phone with your new simcard inserted. It should ask you for your unlock pin. Type in the unlock code we sent you.