Hi,

I bought a friends iPhone 3G. Downloaded a custom IPSW for 3.1FW. Did shift restore worked fine. Now, I tried to run the ultrasn0w. That also went fine.

Now, I have a fully jailbroken iPhone 3G with FW 3.1 but it is not getting the signal from the sim card.

What possibly is wrong here ?

Is it possible that the phone when at 3.0 FW was not unlocked using Yellowsn0w or Redsn0w, as I am not aware of the history.

Thanks, any help much appreciated.

Did you check that the friend had not sold you a phone with the upgrade 05.11.07 baseband that does not work with ultrasn0w?

This is easy to check Settings - General - About - Modem Firmware

Is it possible to downgrade to 3.0 FW ?

PS : I am on Windows XP

Yes it is possible to downgrade to 3.0 FW. Google for this, there are plenty of guides. It is not possible to downgrade 05.11.07 baseband (with the exception of the first batch of 3G iPhones manufactured that have bootloader (not baseband) 05.08 on them. Search for fuzzyband in Cydia and try it out. It's very unlikely it will work, but it is worth giving a try.

@Olethros : Yes, you are correct, I see the modem firmware as 05.11.07

Is there any way out right now....also which is possible on Windows XP ?

Would a downgrade to 3.0 FW also downgrade the baseband ??

Downgrading to 3.0 will not downgrade the baseband. Try fuzzyband otherwise go and tell your friend they sold you a lemon.

sure will try that. and report back.

Well, he has purchased from ebay. I am just helping him out.

tried fuzzyband - says not supported.

Anything else that can fix this issue...or is there nothing we can do at this time

As has been clearly stated all over this forum, by the dev team on their blog, by geohot and everyone who has a solid reputation in the iPhone jailbreak/unlock scene. There is no unlock on the horizon for this baseband version.