When I went to order my wife a new phone I couldn't get a straight answer as to whether or not the T-Mobile full-price version would be unlocked or not. The general consensus was that the device would ship with a T-Mobile SIM and be bound to T-Mobile's prepaid service at least for a couple of months. The whole thing was terribly confusing because you could order an iPhone 5C without a SIM in it at all, which is what I was hoping I could do with the 5S.
I pulled the trigger and ordered my wife an iPhone 5S from the Apple Store online, fully intending to cancel my largest bill, AT&T and move on with the latest and greatest. I value my freedom and at the core I'm cheap, so the long term savings and the short term monthly decrease was highly appealing to me. I had pegged my eyes on StraightTalk, the details of which are destined for another post, and figured we would complete that transition in a few months.
I ordered the phone and it arrived with a T-Mobile SIM. Now I've never done a prepaid plan before so I was a rookie at this in every sense of the word. I opened the box and I could not figure out how to get service started. There was nothing in the box explaining what to do and when I called T-Mobile they basically told me I had invested in a precious paper weight and needed to take it into a store. This was simply not the freedom that I coveted.
I happened to have a StraightTalk SIM laying around and after two T-Mobile customer support calls and three AppleCare calls I came to the determination that this device was most likely unlocked and I could kick T-Mobile to the can.
So here is the bottom line... If you are ordering an iPhone 5S, as best I can tell the device is in fact unlocked. It's worth nothing that I was not transferring a number and I did not have any previous accounts with T-Mobile. I was fed up and frustrated with the ridiculousness of their customer support and took a chance by sticking a StraightTalk SIM into the device - and it worked! My advice if you want to dramatically cut a bill and sport a new iPhone 5S is to not get hung up on T-Mobile when you order as it would appear these devices are free to roam about carriers as deemed fit by their owner.