I just got my unlocked 1st Gen iPhone in the mail today and I'm using it with T-Mobile. I want to turn off EDGE because I currently have no data plan. I installed bossprefs and turned EDGE off but how can I be sure it is off? I notice on the top corner of the display that there is sometimes an E in a blue square, and at other times and E in a white square. What does all of this mean? Thanks.