I have at&t as my carrier. I have an unlimited data plan (normal phone). I've Jailbroken my i-Phone. I notice when my friend opens up HIS iPhone network (General-->Network) settings, he has an option to set up his carriers settings. Why doesn't mine do that? And any time I try to open the internet, it says I don't have a data plan and cannot continue
Have you installed Cydia, there is an app in there(Bossprefs) that will allow you access to these settings.