What is modem firmware?

[Anggrian]

I got my iPhone 4 this week and it's jailbroken with limera1n
and I got situation when I'm going to unlock it as the ultrasn0w didn't worked for my iPhone
some friends of mine said the problem is on my Modem Firmware which is already upgraded to 02.10.04
Then how do I downgrade it so I can unlock my iPhone?
any advice would be appreciated since my iPhone isn't really an iPhone now, without a carrier this is pretty much like an useless iPod Touch

[lelisa13p]

As I understand it, in order to make any mods to iPhone you have to first restore the phone via iTunes. Have you tried that yet? It will reverse your JB and make you factory-fresh, which should resolve your problem re: unlocking. I don't know about the order that you want for both of your items to be successful - both JB and unlock. Sounds like you've tried JB > unlock > fail.

BTW, my iPhone is not JB so I speak to this issue second-hand.

[Anggrian]

you right I haven't tried to restore it
gotta back here with the result
thanks anyway!

[Anggrian]

well I experiencing problem at restoring my iPhone now
any suggestion?

[lelisa13p]

I don't understand what you mean. That is the standard message that appears.

[isot]

Unfortunately most of the modem firmware updates can not be downgraded. This is one of the issues when you want to unlock your iPhone. If you accidentally upgraded your modem firmware and there is not an unlock available for it, you can only use the sim card that you bought the phone with. You can still jailbreak it and install apps, but it will not work with any other carrier.

And yep, it is a normal message when restoring. It will wipe out everything and you will be able to get it back via itunes. However, make sure all your info is properly backed-up.