3GS 4.1 Upgrade Question

[saud0488]

Okay so I'm downgrading my iPhone 3GS on 5.1 to 4.1 so I can jailbreak/unlock with 6.15.00.

My question was, after doing this can I upgrade to 5.1 and keep the unlock somehow? Or would the unlock then be tethered (if there is such a thing)?

 

[BlueRaider]

If your in the US and with AT&T or you know anybody else who is then why don't you call and have it IMEI unlocked? The iPad baseband causes more problems than its worth and the glut of factory unlocked 3GS's has basically made phones with the iPad baseband worth about 50% of a factory, locked phone since it's so easy to get a locked phone unlocked now.

If you decide to flash the iPad baseband check the iPhone dev team's blog to find if Ultrasn0w supports 5.1. Does the phone have blobs saved for any firmware prior to iOS 5.1? If not, have you checked to verify that the phone is old enough to have the iPad baseband flashed to it? Newer 3GS models can be be permanently broken if you try to add the iPad baseband.