I completed my contract on my 5S last fall and I'm now getting around to unlocking it from AT&T's death grip. This morning I got my 5S fired up, moved the SIM card from my 6S back to it, went to att.com/deviceunlock, put in my request, and wait. Here's the problem: It can take up to two days for the device unlock. Does this mean I'm stuck using the 5S until I get notification from AT&T, or is it safe to put my SIM card back in my 6S? I asked AT&T's technical support, and they didn't know.