Hi guys.. My 3GS is running 3.1.3 iOS, for like a year, maybe more, I don't remember when it was done. Since then I got massively screwed by AT&T with a $700 phone bill after they changed my "plan" in the dark of night and didn't tell me. Anyway, I told them to go get f***d and that was the end of AT&T, FOREVER.... I went down and bought a T-Mobile throw away phone and put it's sim in my 3GS and it worked (and still works) just fine. I bought a 1000 minutes for $100 that doesn't expire for a year. Now I just carry it with me when I leave the house just in case of emergency, I no longer use a cell phone to talk to people. I got Vonage for my home and it works fine. But, I don't have internet on the T-Mobile and I can't figure out how to make it work even though the T-mobile website says that you can use an iPhone on their internet. I followed their instructions and no worky.. Well anyway, now I guess I need to upgrade to iOS 4 point something or maybe 5 point something. I don't know if the iOS 5 will work well though on my old phone, I remember the 3G was a nightmare when the iOS 4 came out and actually ruined a lot of 3G phones beyond repair. I don't want that to happen to my phone, I can NOT afford a new phone nor can I afford $1,300 a year for an iPhone contract. So, can I upgrade my 3GS? And if so, what would be my best bet of iOS to use? I could use some guidance here because I really don't know what I'm doing. I do have a brand new, never used AT&T sim they sent me in the mail. It can't be used though because I terminated my AT&T service early this year. But I guess I could use the sim during the hacking ??? I have a screen shot of what the phone is currently running. Oh, and I almost forgot, it IS jailbroken and unlocked. And the upgrade also needs to be jailbroken and unlocked as well for use on T-Mobile. Thanks so much!