I just checked here to see how much it will be to upgrade to the iPhone 4S, and it looks like I’ll be waiting until November 25. If I upgrade before then, I have to pay $250 extra for the iPhone 4S. (See the chart above.)

Another reason to wait until November is that the release date is 10/14, just days before I leave for Japan, and I don’t want to be setting up a new phone a few days before I go on a trip, and be using a new version of iOS. Even if there aren’t any major bugs in the OS, a lot of apps probably don’t work that well with iOS 5.

There’s also the option of switching to Verizon and paying the early termination fee to AT&T, which is calculated this way: $325 minus $10 for each full month that you’ve been on contract. I got the iPhone 4 when it came out 13 months ago, so the fee works out to $195.

So if I really wanted the new iPhone 4S, it would be cheaper to pay the $195 early termination fee and switch to Verizon than to pay an extra $250 to stay with AT&T.

As to why I think AT&T knows exactly what they’re doing, I think there was at least one high-level meeting on the pricing, and they figured that they could profit from people who want the new iPhone but won’t or can’t switch carriers, maybe because AT&T is the only carrier with service in their neighborhood. Price it just high enough above the termination fee so that the increased revenue offsets the people switching.