Ok I got my codes, as in plural. There are two, a network unlock code, and a service provider unlock code. First let me tell you that the instructions from unlockonline.com are wrong, or maybe they only work on a phone with the stock rom. It says to put an unauthorized sim from another carrier in, reboot the phone, and you will be prompted to enter the code. Well that doesn't happen with this phone, at least not with the Straight Talk sim I used. It is an old inactive sim though, so maybe that is why.
In any case I followed the video instructions Game Theory posted from unlocklocks.com, in which they show you how to use the dial pad to bring up the correct interface to put the codes in. Using that I was able to enter the service provider unlock code, which worked. When I tried to enter the network unlock code I got a message stating that the phone wasn't personalized.
Does anyone know what that means? Unfortunately I can't do anything else at the moment. My personal phone is on MetroPCS, and I don't have any other sim cards here to put in. I'm wondering if after I put my brother's sim in the phone if I will then be able to enter the other code, or perhaps the other code is simply unnecessary.