I have a 3G iphone 3.1.3& 05.12. I unlocked the phone few days ago via ultrsn0w in Cydia. However, I can't recieve or send MMS. Also can't get on the internet. When I go to Settings>General>Network,there is no field for "Cellular Data Network", to enable me modify APN settings. I have read several post over the past four days to help me fix this problem but to no luck. The last thing I tried was, going to Unlockit - APN Changer for your iPhone to create profile for T-Mobile. Didn't help. As it stands now, I'm hesitant to upgrade to IOS4 cuz I'm not sure what it will do to my phone. Can any please help? Please someone.