So I upgraded one line on my account to get the 5s on my line. In the past when doing this I've simply swapped sim cards. But when I tried this today I got a screen during the iPhone 5s setup prompting me to activate this with the number I upgraded. I then gave up because I didn't want to mess up the SIM from my line that was in the 5s and I also don't want to end up disabling the phone that is on the line I upgraded. Help. How do I do this?