Thanks for all the good advice! I always sell my iPhone a few days before the new one comes out, most of the time. When I get the new one, it's always been under a 'new' two year contract. So, I guess I never had a problem before with that. This time I'm buying a full price one from Apple, and I understand that I'm still under a two year contract with my phone line till April 2016, but I wasn't 100% sure that would affect my old phone that I'll sell in a couple weeks, when the new one comes in. I'll call them and make sure, after I get the new phone in.
I should only have to switch SIM cards I would think and let them update it on ATT's end with the new phone info. Just don't want to be stuck waiting till April 2016 to sell my old phone, that would suck. I doubt they will unlock it till after that date. You have to fill out a form online and wait a few days to see if they approve it. I've tried doing it before for a friend and never got anywhere with it, and ATT will not discuss anything about it over the phone, have to use the website they give you. So, tired of ATT after all these years of trying to get a new phone on the first day and they don't have stock ready online. Same thing happened last year and was on their website 15 minutes before the sell was supposed to go live. Didn't get the phone until Oct. 10th, which made it make my agreement date, that much later.
Next plans do not work for me. May eventually have to get a new plan, but I pay $39.99 for 450 minutes (which I never use), $10 for unlimited text (they dropped the price from $20 for me last year), and $30 for unlimited data. So with a company discount I pay less then $80 for my one line that works for me. I don't have anyone else to shack up with to get a better price option for more lines. Tried before with friends, then they pay late, etc. Happy with my simple plan.
Thanks all!