How do you downgrade your iPhone from 4.1OS to 3.1.3?

[BrandonKobayshi]

Hey everyone! I just bought my new iPhone 3gs yesterday! Yay! But theres 1 problem, Spirit doesnt support the 4.1OS firmware just yet. So I was wondering how do you downgrade the 4.1 firmware down to a 3.1.3? Ive already tried MANY things and non worked! If your answer works for me I would greatly appreciate your help and appoint you BestAnswer to my question.
P.s. I have a mac, if that helps any

 

[Tranceinmy335i]

Alright well download the 3.1.3 ipsw, put the iPhone in DFU mode and press Shift restore. This will downgrade your iPhone, and download Tiny Umbrella to kick it out of DFU mode at the end of the process.

Now if you saved your SHSH blob in Tiny Umbrella you would have no problem, but im guessing not since you just bought it.

 

[Jebidiah]

You would need to get a hacked copy, it's called jailbreaking.

The only problem is, it voids all warranty (i think apple know when it has been jailbroke, both at present or previously) so it's not reccomended.

But just search out jailbreaking on google and you will find out about it. It has some nifty features that apple really should incorporate. Every firmware update they incorporate some of the ideas (not all of them to avoid making it look like they are submitting to the fact the jailbreakers are delivering the best out of the iphones/ipods)
you can set custom themes (lockscreens wallpaper etc) download nice apps, able to watch flash videos on sites other than youtube, etc.

But again, if you feel you will need your warranty, don't do it and just wait for spirit to update.

One last word, new iphones usually only support the recent firmware update so make sure to have a backup.

 

[SeanParnes]

I had to do the same thing with my iphone when i wanted to jailbreak it, first you go to google and then you type in downgrade itunes version and you will have a whole list of options, there are a ton of websites that work and now i have version 3.1.3, it is very simple.