Yes, you read it right! Unlock for iPhone 4 02.10.04, 03.10.01 baseband is SIM dependent. MuscleNerd confirmed this in a reply to his follower on Twitter. SIM dependent means that the unlock only works on a particular SIM card, which in this case is a T-Mobile SIM only. Moreover, the baseband of iPhone 4 runs ThreadX, a RTOS (Real-Time Operating System) with multitasking kernel which makes it further hard to unlock.
@MuscleNerd how much longer would it take? Weeks or months?...seriously thinking about selling my iphone4...
@Cleansman there's no way for us to know. We were making great headway with one version til we realized it was SIM dependent (!)
@impulse29 For that one, we considered a method where you could "fix" the SIM to work with it, but far too complicated for widespread use
According to MuscleNerd, he has two T-Mobile SIM cards but the unlock worked differently on each of them. He has figured out a workaround which involves fixing SIM card of any carrier to make it work with the unlock but that method is too much complicated for the widespread use.
@bh8ti the crashes still exist (and in fact can be used on the 3G/3GS). Using these particular ones on the i4 is the issue
MuscleNerd further clarified that Sherif Hashim's exploit which crashed both of these basebands is still valid but implementing it particularly on iPhone 4 is not that easy. The same exploit is already in use for the unlock of iPhone 3GS/3G on iOS 4.2.1.
Stay tuned while we update you with the latest news on iPhone 4 unlock.
Update#1: iPhone 4 Unlock is Possible Through NCK Brute Force Method
Update#2: What is Gevey SIM Hack & How Gevey SIM Interposer Work to Unlock iPhone 4?
With Apple knowing how difficult it is to exploit the 02.10.04 baseband it seems to me that they will incorperate it into their future productions, it has been now almost 2 years since the introduction of this BB and still no exploit other than the interposer or the AT&T factory unlock