Ok, here are the facts: iPhone 4S sold by Sprint has both CDMA and GSM capabilities. Sprint will unlock your iPhone for international GSM use, but not for domestic carriers like ATT, Tmobile, or even CDMA Verizon. My iPhone 4S has been unlocked by Sprint and will work abroad. I want it to work with Tmobile or Solavei here in the US. My question is: If it has GSM capabilities and it's already unlocked for international GSM use, is it at all possible to get my Sprint iPhone 4S working on Tmobile US? I've read that you can buy a 128k SIM card and that solves the problem but I'm wanting confirmation or any other tips or jailbreaks I could possibly use to make my iPhone usable on Tmobile. My main motive is not really to get away from Sprint, it's to make my iPhone worth something if I need to sell it after my contract is up. As it stands, I can not sell my iPhone for anything because nobody wants to use Sprint because everyone knows how bad it is. That makes my iPhone worthless. That pisses me off. I used to be able to sell my iPhones every year, pay out my contract, upgrade to the new iPhone, and be left with $20-$100 for the whole transaction. When I tried to do that for the iP5, I was shocked when someone offered $250 for my iP4S with 64GB. So again, any help from anybody who has tried this would be greatly appreciated. I already bought some 128k SIM cards to try out and I'll post results when I get them.