So I have a 5 and an upgrade on two lines. I'm thinking about purchasing a 5s on one line and selling it (using an upgrade to get the subsidized price), than using the other upgrade for the 6 when it comes out. I remember when I purchased my 5, it came locked, and I had to enter part of my social security number (I think) when I got it. Is ATT still doing this? Will I have to open the seal, activate the phone on my line, than deactivate it, before I sell it?