I have a question about how to update an iPhone 3GS that has already been jailbroken and is also carrier unlocked. I attend SGU on the island of Grenada and got the 3GS prior to leaving, which was August 2010, making AT&T still the sole provider. Once I got to Grenada, I took the phone to the Digicel store (one of two providers on the island), where they jailbroke the phone, put in the Digicel chip and set it up for use on their network, where it works fine - except the data speed is horribly slow if you're not running on Wi-Fi. The phone is running version 4.0.1 of iOS and I'm wondering how I can update it to 4.3.3. I've been reading online about how to do it and it all seems simple enough, but I'm wondering if there's a way in which I can update it that won't erase everything that's on the phone (contacts, texts, apps, etc). I also want to ensure the update doesn't interfere with the carrier unlock. Thank you!