Just my input: I have a Blackberry storm 9550 from Verizon that uses CDMA and GSM. I had this phone unlocked and was able to use an ATT sim card on it with no problem. I also unlocked my Blackberry 9860 model from ATT and installed a Verizon 4G LTE sim card in it and it would not take. However, I place the Verizon sim card in the unlock Verizon BB 9550 and it recognized it and I activated it, now I placed it back in the Unlocked ATT BB 9860 phone and voila! it working great! Now I have two phone that can operate on both ATT and Verizon network.