hi all

I'm looking for advice on how to downgrade from v4.0.1 to lower

Its also locked to O2.

The phone is jailbroken having used redsn0w 0.9.5b5-5

Ive read that Ultrasn0w can Unlock the iphone, but I don't have access to wifi.

Can anyone explain how to do this?

Thanks

You can downgrade a 3G to any firmware, they do not use the SHSH checks.

Download the firmware from iClarified. Open iTunes, shift-restore, point it at the old firmware. When it completes and errors out (expected behavior), run Firmware Umbrella and click 'Kick device out of recovery mode'.

That's it.

Worked a treat thanks.

Any knowledge on how to unlock from O2 to be able to use any SiM card?

Depends on what firmware revision you've restored to, but yea, the tools exist to do so and are documented all around. Take a look in the spot specifically for the model / firmware you're using and you'll see. Here's a quick reference:

3.1.2: redsn0w / blackra1n for jailbreak, ultrasn0w for unlock
3.1.3: Spirit for jailbreak (need legit AT&T SIM), ultrasn0w for unlock, Spirit2Pwn for pwned bootloader
4.0: redsn0w 0.95b5-5 for jailbreak, ultrasn0w for unlock

Poke around and you'll find tutorials for these if you need them -- iClarified is a pretty reliable source for tutorials on what you'd need to do.

Since you've got a 3G, it's pretty easy, nothing too crazy.

Originally Posted by tsam19

Worked a treat thanks.

Any knowledge on how to unlock from O2 to be able to use any SiM card?

O2 in the UK will properly unlock the iPhone - for free if you have fulfilled your contract. If you are still on contract - then you should contact o2 to find out how much the unlock will cost.

Otherwise you can use ultrasn0w 0.9.3 - but you need to be careful about upgrades.

I've downgraded to 3.1.3 & created a 'custom ipsw' file with Cydia integrated.

Installed ultrasn0w through Cydia & activated all the network carriers.

Fantastic!

I will remember not to update via Itunes.

Thanks to all.