Unlocking iPhone 3GS iOS 4 Baseband 6.15.00 Failed Unlock Attempt with Ultrasn0w 1.2.5

[MgXII]

Hello,
I *accidentally* upgraded my iPhone 3GS from firmware iOS 4.1 (BB 6.15.00) to the stock iOS 5.0.1. I attempted to jailbreak it, but I did not like the tethered jailbreak. So, I decided to downgrade back to iOS 4.1. I did some research prior to this and I found out that there could be issues with the baseband, but I was skeptical to flash it with the iPad baseband due to the irreversible consequences. So after a few iTunes errors, I successfully downgraded my iPhone to iOS 4.1, jail-broke it, and attempted to unlock it. However, I'm have difficulty unlocking it. I installed ultrasn0w 1.2.5 just a few minutes ago, but my phone is still locked. It searches for a network, then gives up and just displays "No Service."
I'm wondering if this has something to do with the inconsistent state of the baseband, according to the Dev-Team's blog. Could someone please guide me through the steps of fixing this issue? And what may the consequences of flashing with the iPad baseband? I really don't want to fry my iPhone because of a minor mistake. Your help is greatly appreciated, thank you in advance!

[keenpois0n]

I saw a statement from the dev team saying that the iPad bb will not work on new iPhone 3gs's made after week 35 this year, so is yours a new iPhone? if not, try reflashing the iPad baseband, that seems to get it for some

[MgXII]

I checked through device manager, the bootrom for it is 359.3.2. However, the 4th and 5th digits of the serial number are "08". Which values should I look at, the bootrom or the serial number?

[keenpois0n]

that means you've got a new bootrom. I think its the 4th and 5th digits of the serial number youll need to look at

[MgXII]

Hello,
I *accidentally* upgraded my iPhone 3GS from firmware iOS 4.1 (BB 6.15.00) to the stock iOS 5.0.1. I attempted to jailbreak it, but I did not like the tethered jailbreak. So, I decided to downgrade back to iOS 4.1. I did some research prior to this and I found out that there could be issues with the baseband, but I was skeptical to flash it with the iPad baseband due to the irreversible consequences. So after a few iTunes errors, I successfully downgraded my iPhone to iOS 4.1, jail-broke it, and attempted to unlock it. However, I'm have difficulty unlocking it. I installed ultrasn0w 1.2.5 just a few minutes ago, but my phone is still locked. It searches for a network, then gives up and just displays "No Service."
I'm wondering if this has something to do with the inconsistent state of the baseband, according to the Dev-Team's blog. Could someone please guide me through the steps of fixing this issue? And what may the consequences of flashing with the iPad baseband? I really don't want to fry my iPhone because of a minor mistake. Your help is greatly appreciated, thank you in advance!

I managed to find a fix for my issue. I figured I'd post it in case it's of any relevance. This procedure worked in my case, so I would not just attempt this out of the blue. Do some research, ask around and explore other options, first.


I posted the same question on the Dev-Team Blog, and one of the moderators said that I should re-flash the iPad baseband. They also said that since my phone was already on the 6.15.00 baseband, that someone had flashed it before, and therefore doing again wouldn't do any more damage. I took the following steps:
1. Restored my device to 4.1 using iTunes 10.4
2. Applied redsn0w_win_0.9.9b9d (found on Dev Team's blog) and jail-broke my device by just checking on "install Cydia"
3. After the device booted up, I applied redsnow once again to re-flash the iPad firmware. For instructions, i did a Google search for "Re-flash 06.15.00 Baseband With RedSnow"
4. After the device booted up, I went into Cydia and installed Ultrasn0w 1.2.5
5. Re-booted the device, inserted a T-mobile SIM card, but the carrier wasn't displaying. All I had was "searching..." or "no service".
6. I took the sim card out, and applied the re-flash once more.
7. After the device booted up, I inserted the SIM card and saw one signal bar ( no carrier name). At this point, I rebooted once again. In the end, once the device booted up, I had full bars and the carrier name was displayed. So in the end, it worked.

Again, this procedure worked in my case. I would not advise following these steps unless you absolutely know what you are doing.