That's what official R-SIM site says about R-SIM 4 unlock on iPhone 4 4.11.08 & 4.12.01 basebands:
You can now unlock your GSM iPhone 4 with the new R-SIM IV. will work for iOS version 4.1, 4.2, 4.2.1, 4.3, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 5.0, 5.0.1 and 5.1 with modem firmware 1.59, 2.10, 3.10.1, 4.10.1, 4.11.08, 4.12.01. Be sure to check your firmware version before purchase!
The new R-SIM IV unlocks your GSM iPhone 4 running iOS 5.1 and earlier and now supports modem firmware versions 1.59, 2.10, 3.10.1, 4.10.1, 4.11.08, and 4.12.01. Currently, a tethered Jailbreak is available for iOS 5.1 for iPhone 4, and you will also need to install the latest Furious Mod file for proper operation.As you can see there's no big difference between R-SIM 4 and Gevey Ultra 5.1 tools, you still have to jailbreak your device and install Furious Mod from Cydia in order to get your device working in normal mode. Update: Use this link to find out how to use R-Sim 4 to unlock iPhone 4. The only significant difference is the price: R-SIM 4 can be obtained for $19.99 from official site when for the new Gevey Ultra solution you'll have to pay whole $49.99. Those hardware solutions are now under a big question mark as now wee have a nice and free SAM unlock that can unlock any baseband on any iPhone.
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