Sim-free

I

iMore Question

Any one know when i can purchase a "sim-free" unlocked iphone 6 plus. I was told by apple that the "contract free" phone is actually locked to tmobile. Apple said if you by that model tmobile could unlock it for you, but it would be up to tmobile to do so. Since I currently use AT&T I would prefer to buy a sim-free version. I see the UK apple site is listing a sim-free version but not the us site. Thanks in advance