Hi all - I had my iPhone 3GS replaced by Apple in November 2010 (replaced by a refurbished unit) and tried to jailbreak with PwnageTool and redsn0w with no luck. I am currently running an official 4.2.1 (8C148a) iOS on my iPhone 3GS. Is there any way I can jailbreak this phone? I would like to stay with 4.1.x or 4.2.x iOS, if possible. I would prefer an untethered jailbreak, if possible. I want to jailbreak primarily so I can tether free of charge on AT&T. So which jailbreak would work for me? Is there a guide to allow tethering, or do I have to pay for an app in Cydia (which)? I used a guide to tether on my previous 3.2.x jb). Also, can I unlock my phone? Which method? Thank you!