So I was wondering, I have a blackberry bold 9900, from tmobile. I was trying to sell it and someone offered to trade me cash plus the same phone but for at&t. Now I have called the tmobile store and asked if I had the at&t phone unlocked if I could still get 4g. She told me no so then I said if I could delete the vendor file that we are all familiar with and load the tmobile 0S7 on it if I could get 4g then. She had no clue. Does anyone know the answer to this?