There was a lot of confusion amongst Apple employees at my nearest Apple store regarding the unlocked iPhone 5s. Not a single Apple genius knew that T-Mobile iPhone 5s when bought at full price is in fact unlocked for global GSM use. I was kind of a guinea pig when I challenged the Apple genius into saying Apple’s website clearly states iPhone 5s model A1533 is unlocked for global use. It works with any GSM carriers including AT&T and T-Mobile with full LTE access no less! That is the number of LTE bands packed into the iPhone 5s.
I then proved by purchasing an unlocked iPhone 5s (A1533 model) which they said it is locked to T-Mobile. Popped my AT&T SIM in the iPhone and voila, AT&T with LTE on a T-Mobile locked iPhone 5s! It cost a pretty penny though – $697 including taxes in California but I think it is justified given that I am an year due out for an upgrade at AT&T and they want more than $500 with a 2 year contract!