I just purchased a 'new' unlocked Note 4 per the description of the item. Now I've never done this before so just excuse my inexperience with all this. I open the box and it says that it's an ATT phone! I don't plan to use it with ATT and I don't want whatever ATT has done to change they OS to suite them. Nothing in the description says it's an ATT phone. Am I wrong? Is there such a thing as a plain old Note 4 GSM phone unadulterated by any carrier?? Should I return it? I plan to use this with T-Mobile prepaid.