Why will my iPhone not work with Straight Talk?

I have an iPhone 3gs, updated to 6.1, that I'm using for Straight Talk. The texting, calling, and Wi-Fi work but not data nor mms. I jailbroke it, used Tetherme from Cydia, entered all of the APN settings correctly several times (for Tetherme and Network), tried using unlockit.co.nz. I have watched several videos, read several forums and blogs, went to Straight Talk's site, went to the Straight Talk iPhone Wikipedia site, and so on. I have tried everything that I can find online. Why will nothing work?

There's the possibility that the phone has a bad ESN, which could explain all of your problems right there. There's an equal chance that the SIM card that Straight Talk gave you is faulty, which would also cause the problems you describe.

Try calling Straight Talk customer service and have one of their "customer service" people try to figure the problem out. If that fails to work, and the phone has a clean ESN, then you might want to try undoing the jailbreak and trying the setup from factory specs.

There's no easy answer to problems like this, considering the lack of training that Straight Talk gives it's workers.