Upgrade to 16GB iPhone without changing contract

That's all cool, fine and dandy, but what do you then do with the old 8gb iPhone? That set of instructions on that link you provide does not give instructions of how to use the old 8gb iPhone with another number.

I thought it would be as simple as just inserting the new SIM into the old 8gb iPhone and then restore and then activate, where you would then enter the 2nd phone number of your mobile account. This didn't work in my case. For some reason, the 8gb iPhone would only work with the old SIM card. The message I kept receiving from iTunes when I tried to use a new SIM card was that it was an Invalid SIM Card. Since the Genius Bar people also got that message and were able to confirm that the 8gb iPhone was working just fine with the old (official AT&T iPhone) SIM card, they concluded that the 8gb iPhone was defective.

They resolved this issue by swapping the old 8gb iPhone with a new one. Nice for me. I even suggested that they activate the new SIM card using my 2nd phone number and then once that SIM card was activated they could just put that into my old 8gb iPhone. Mainly because that old 8gb iPhone had a nice ShieldZone screen and phone protector ($24.99). But I guess the Genius reps were in a generous mood that day and decided to bless me with a totally new 8gb iPhone for all of my troubles :) . Caveat emptor however, this may not be your outcome should you find yourselves in a similar situation as I did yesterday.

That's a good question, and to that o2 say that you need to purchase a new SIM from them for £4.99. So I gather in the US you MAY indeed need to get a new SIM from ATT.

The info on that link is exactly what I did yesterday. I guess my old 8gb iPhone must have been defective or something then :)

This didn't work for me - I had the same problems as apeguero. The iTunes message indicated that we needed to get a new SIM from AT&T.

Specifically, I was able to put my old SIM in the new phone, but now neither the old SIM or the new SIM will work in the old phone.

But that was an 8 GB for 8 GB swap. It's sounding like there's some difference (perhaps at the firmware level) that is blocking the use of an 8 GB iPhone's SIM in a 16 GB model... or something.

Exactly what the Genius did when he replaced my iPhone due to screen issues. Gave me a new phone and simply swapped sim cards. Nothing more.

"Mark Siegel who is the Executive Director of Media and Analyst Relations with AT&T emailed iLounge to tell them that if you choose to upgrade your iPhone from 4 or 8GB to the new 16GB, your contract will be backdated to the starting point of your original iPhone's activation date."

Don't let your hatred disguise the facts. Your contract will be backdated, no contract extension.

But in the case of some of us where we're not only replacing our 8gb iPhone with the new 16gb iPhone, we're also giving it to another member of our phone plan, in my case I gave my old 8gb iPhone to my wife. Since my wife's phone was not an Iphone, this means that her line would have to be converted over to iPhone plan. This, in the end, extended our contract for two more years. Simple as that. I'm going to talk to a buddy of mine who manages one of the local AT&T stores in my area to see if something could be done about not extending it but I'll be honest, I have no hopes. Good thing AT&T has given me good service so far and their rates are competitive.

Seeing as it's an entirely different phone - one with 16 GB vs. 4 or 8 GB, of course you have to pay for it.