I know that this forum is populated with lots of folks who use Sprint MVNOs who use older phones. For those of you who have older iPhones that Sprint won't unlock for domestic use, I've found that there is indeed a way to unlock your phone to go to T-Mobile or AT&T. It involves using a SIM interposer that overlays a regular SIM. The specific one I have, however, only requires the interposer on initial unlocking. After that, you can remove the interposer and just use a bare naked SIM. However, the phone relocks if you perform a factory reset, and you have to go through the process again to make the phone work on GSM.
The specific device that I used is called a Magic SIM 8x and seems to have been developed by someone in Thailand. You will need a bit of tech savvy to go through the unlocking process. This specific interposer is hard to find on eBay.
For the 4s, you will also need to splice a very thin piece of scotch tape to secure the interposer onto your nano-SIM, and then make sure that both fit snugly into a micro-SIM adapter.
Anyone have experience with using Gevey or R-SIM to unlock their older Sprint iPhones?
