T-Mobile "No Service" after upgrading to 5.0.1 iOS + 6.15.00 firmware

[James Duong]

So I recently upgraded my Iphone 3GS Old Boothrom to 5.0.1 iOS with 6.15.00 firmware.
First I did an apple restore from itunes then used redsnow to jailbreak it with 5.0 iOS.
When everything is done with redsnow, I reflashed the baseband by installing the jailbreak again, but this time without Cydia. After loading to the iphone menu, I installed ultrasn0w from cydia and restarted the device. All applications and device work perfectly.

BUT!

When I insert my T-mobile sim card in , it does not seem to have any service at all. (No service)
Am I missing any steps in this process?
Any help would be appreciated.

[[email protected]]

Do you have it jailbroken? I don't see cydia on it for you to put ultrasn0w.

[James Duong]

Yes it is jailbroken, my cydia is on the 2nd page.

[[email protected]]

If you already have ultrasn0w on it and it's not working you may have to reflash the 6.15.00 modem firmware.

Sorry-- I see the whole first part of the post now... For some reason it wasn't showing up at first. My apologies.

Make sure it officially activated. You may need samprefs or redo it and activate with AT&T sim if you are in the U.S.

[James Duong]

How would you reflash with your method?
I tried mine but it doesnt seem to detect the carrier.
(Open redsnow -> Jailbreak -> uncheck install cydia, check install ipad baseband -> wait till it completes and insert the sim in)

is there another way to do it?

[[email protected]]

No that's how I would do it- I didn't see you did all of that- earlier it wasn't showing. but have that official sim handy if you restore again so you can activate it with an official carrier. Hactivation messes up a lot of unlocks.

[iYeow]

Ultrasn0w 1.2.4 is compatible up to iOS 5.0, not 5.0.1 yet. You need to downgrade your firmware to get signal

[James Duong]

Oh now I see the reason why I did get any signal.
Do you know any links that show a downgrading process from 5.0.1 to 5.0.
Thanks a lot

[[email protected]]

Good catch. I didn't think about that.

[iYeow]

I think apple has stopped signing 5.0, you can try to restore to 5.0 . If it says ineligible , then 5.0 is history. You can however, downgrade to custom firmware of 4.1 for 3g and 3gs without saved blob.

[sbruns77]

Mr. Duong I went through the identical steps as yourself. Please do post if the above steps prove successful. Best of Luck!