So my 5s came today and I'm trying to get it set up and running. I had thought that all I needed to do was swap my 4g sim from my old 5 to my new 5s and then sync it with iTunes. Imagine my confusion when I saw that the new 5s came with it's own sim card. The directions say to call a number from a separate line to activate LTE. Do I really need to do all this? Will simply putting my old sim in my new phone not work?