[ricardobeat]

My original carrier is from Brazil, and I can't see their APN settings, but I've used three SIMs in Europe from different carriers and they all worked seamlessly, and was able to look into the APN settings for at least one of them (Wind, I think).

To me this looks like an issue of Straight Talk failing to fulfill their job as a carrier, or AT&T not providing the necessary access to their resellers. If you're going to sell mobile plans you should have the infrastructure to support it (third-party or not).

[nathana]

Right, so the Brazilian SIM card was issued by a carrier that has a carrier profile included with iOS that is set to block access to that menu, while the European SIM cards you have either were issued by carriers with carrier profiles in iOS that don't block access to that menu, or those European SIM cards were issued by a carrier or carriers that the iPhone knows absolutely nothing about (no built-in carrier profile(s)).

In my case (and in the case of some other customers of other MVNOs), my carrier, Straight Talk, is really just a company that buys wholesale access to AT&T's network and then resells it as a prepaid service to customers. Thus a Straight Talk SIM card looks identical to an AT&T SIM card to the iPhone. And AT&T's iOS carrier profile blocks access to the APN editing submenu. So my situation is different from yours because in your case, your Brazilian service provider and your European service providers had no corporate connections with each other, nor did they share a singular common network, as is the case with AT&T and Straight Talk.

There is next-to-nothing Straight Talk can do about this, at least without both AT&T's and Apple's co-operation.