The iPhone 4 was capable of HSPA+ on AT&T, but was blocked by the OS. Does anyone know if iOS5 opens that capability up or are they just limiting it to the 4S now?
The AT&T iPhone 4 uses a X-Gold 618 baseband, which is not capable of HSPA+. The CDMA iPhone 4 baseband is capable of it, but cannot be activated because it lacks s SIM card.