As title says I have a 3gs running 3.1.3 mc134b and modem firmware 05.12.01. If I upgrade to os4 can I jailbreak and unlock this again and if so how. I have looked around and there are so many options now I don't know what is what. I need to be able to unlock as I am using it on three and Its locked to vodafone. Thanks in advance for any tips you can give me.