There's no such thing as a software unlock for the iPhone 5. Software unlocks only work on the 3G, 3GS and a handful of remaining iPhone 4's which still have the 01.59.00 baseband
That isn't true. From what apple told me when I bought my 5s is that they are all unlocked until you put in the carrier sim, then it lacks to that carrier. In my case, I bought it unlocked from apple and when I put in my sim, something it downloaded told it to remain unlocked.