If you’re going to switch to AT&T for the iPhone, why not get a second phone for almost nothing?
If you order the Nokia N75 from Amazon.com for $25, that will start your new two-year contract with AT&T. Then, activate the iPhone, which resets that two-year contract. Thanks to iPhone not bearing any penalty for upgrading (unlike all other AT&T devices), you are essentially resetting a two-year contract back up to two years.
Would you like 3G with that iPhone? Buying the N75 first gives you that ability…
If you buy the N75 first, you get a S60 smartphone with 3G. You can then SIM swap between iPhone and the N75 when you want to bump up to 3G data. This is great for if you want to have a 3G wireless modem for your MacBook or Windows laptop, since it only takes a few seconds to pop the SIM into the N75. And, the iPhone data plan supports all Cingular devices (with the exception of AT&T’s Cellular Video and Video Share services).
With iPhone now out of stock almost everywhere, now’s a great time to set up your AT&T account, get a free phone. The Nokia N75 also has a $25 mail-in rebate from Amazon.com, so you actually get the phone for free.