Hey everyone, I recently sold my 3GS (Telus Network) to somebody who was looking to use it as a replacement for a Bell Network phone. The phone was jailbroken on iOS 3.1.3. After agreeing to meet with a buyer, I wiped the phone of all my personal information and upgraded to iOS 4.3.5, un-jailbreaking my phone in the process. The phone had a baseband of 5.16.02. However, it being my first time selling a phone, I was unaware that I had to personally unlock the phone. I was under the impression Telus or Bell would charge a fee to unlock the phone themselves. I realized I was wrong when the buyer brought the phone back to me asking me to unlock it for her. I told her I'd need a day or so to work on it. I originally tried a tethered jailbreak of iOS 4.3.5 but I was having so many issues unlocking with ultrasn0w that, after a series of Google searches and endless syncs, I ended up downgrading the phone to iOS 4.1 with a baseband of 6.15.00. After jailbreaking the newly installed iOS 4.1 (BB 6.15.00) with redsn0w and using ultrasn0w to unlock the carrier, it finally worked. I replaced my Telus SIM card with the buyer's Bell SIM card and managed to connect to the Bell 3G network. Made a call and everything. So that's settled. However, the buyer wants a non-jailbroken phone. She's worried about security vulnerabilities and whatnot. My question is: If I were to un-jailbreak the 3GS by restoring the phone to 4.3.5, would this undo my efforts to unlock the carrier? Thanks so much to anyone who can answer this.