The iPhone stands out from most cellphones in plenty of ways—no buttons, all touch screen, gigabytes of memory. But one of the most radical differences is the way you sign up for your cellular service. It's not in a phone store with a salesperson breathing down your neck. It's at home on your computer, in iTunes, where you can take all the time you need to read about the plans and choose the one you want.
The signup process pretty much explains itself. But it's worth noting a few twists and turns you'll meet along the way.
All of this, by the way, requires iTunes 7.3 or later. (In The iTunes Window: What's Where for details on getting this software for Mac or Windows.) To get started, put the iPhone into its cradle, and plug that into your computer. iTunes opens automatically, ready to begin.
Activation means signing up for a plan, turning on the service, and either finding out your new phone number or transferring your old number to the iPhone.
Until you activate, the iPhone can't do much of anything. It can't make calls, play music or video, or get on the Internet. So no, you can't buy an iPhone and hope to use it as a fancy iPod: Without an AT&T account, it just won't work. Signing up for AT&T service is required.
For that matter, the iPhone is a locked GSM phone, meaning that it works only with an AT&T account. It won't work with ...