Sorry if this has been posted a million times, I quickly searched with no answers. I pre-ordered this morning a Gold 6s Plus iPhone that I want to use on AT&T. I couldn't click AT&T to put in account info as it is on a business plan so I clicked contract free and T-Mobile. That phone will come unlocked and work as it is GSM, correct? Below are some images of what I am talking about. I just have to put my iPhone 6 Plus sim card into the new phone and everything should be great? Thanks!