How do I know they work though? Have you some proof?
Gee, I don't know where you have been, but TurboSIM from Bladox (check the forums at bladox.com) was the first such device to be used to 'unlock' the phone functions of the iPhone.
The TurboSIM had been on the market since 2004. The fact that it could be 'programmed' led to it being used with applesaft to 'unlock' any iPhone - be it a USA AT&T or a UK O2.
TurboSIM can be used for so much more than just 'unlocking' check out the details at Bladox.
All the Chinese and Taiwanese devices do is copy the one function that allows the 'unlock'. They cannot be erased and re-programmed. Theoretically some of them could be, but.... we don't have the tools to do it.
I have been trying to get all the devices for testing. I think I have most of the "single SIM" solutions now. The so called "piggy-back" SIM devices.
I have tested the TurboSIM; and the first, second and third generation Chinese devices; and the HyperSIM from Taiwan.
All 'work' and fool the iPhone. The TurboSIM has consistently been the best. However, the HyperSIM from Taiwan and the 3rd generation Chinese device have been very good with USA iPhones.
I think the only way you will belive they work is for you to get one and try it for yourself. There is no way someone else can prove it for you.
A3 Australia