This might seem strange, but how do I go from 3.0.1 to 3.1.2 or 3.1.3

[mimo777]

I haven't touched my phone since I first got it and jailbroken it, but the wifi tethering, netflix, and other apps are complaining that I am at 3.0. I want to go to 3.1 and my cydia application has a list of SHSH with iOS 3.1 through 4.1 in green but it doesn't look like the examples in the guides. Does this mean I can't go back to 3.0 and does it mean I can go up to 3.1.2?

[iYeow]

That is correct, you can't go back to 3.0 but you can go anywhere from 3.1 to present update. Note : even if you can downgrade /upgrade fw, baseband once upgraded cannot be downgraded.

[mimo777]

So theoretically can I just update to 3.1.2(in itunes) and go to jailbreakme.com, and does this prevent me from unlocking or tethering(wifi not to boot)