The original GEVEY™ Ultra unlocks your GSM iPhone 4 and 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*,5.1* and 5.1.1* and must have modem firmware 1.59.00, 2.10.04, 3.10.01, 4.10.01.Please double check your iPhone 4 modem firmware before ordering (Settings-->General-->About-->Modem Firmware). Please follow us on Twitter at www.twitter.com/applenberry for latest update on modem firmware 04.11.08 and 04.12.01..