At the time I wrote the iPhone review, it was not clear to me (or anyone) how iPhone would behave if the device were activated, a process that requires a two-year commitment to AT&T Wireless, and the AT&T Wireless service were subsequently cancelled. I called AT&T yesterday to cancel my service, something that you can do without penalty within 14 days. My iPhone’s only been one day without AT&T, but so far, all of the device features that don’t rely on the cellular network–pretty much everything but Visual Voice Mail–work without issue. And if I had to call 9-1-1, I could.The only sign that anything’s amiss is “NO COVERAGE” where the carrier name, mobile net signal bars and EDGE data indicator appear.The first and final AT&T bill for iPhone service comes to about $69. That covers activation and 12 days’ worth of prorated service. Is activate-and-cancel smarter than using the unbricking crack? Users who have applied a “crack-tivation” technique to unbrick (i.e. get past the “Activate with iTunes” lock screen) their iPhones have found that YouTube does not function, and that other applications that use the network complain about not being able to find an EDGE connection before they connect with Wi-Fi. I haven’t had any of those problems, but I can’t say what would happen if I did a hard reset on iPhone or wiped out the MacBook Pro that I used to activate it. I also don’t know whether Apple’s first iPhone software update will re-brick my iPhone.It shouldn’t. The SIM is valid. It’s in the same state it would be in if I had missed a payment, or if I were out of wireless range and couldn’t register with the network. Even so, I’ll turn off the GSM/GPRS/EDGE radio to save a bit of battery.AT&T was very quick and courteous. I was impressed with the professionalism of the AT&T reps that handled my cancellation. I only had to talk with two people, neither of whom gave me a hassle. My contribution to the “how can we keep your business?” exchange was an offer to stay on if AT&T would let me add data service for another device onto my account so that I could move iPhone’s SIM between two handsets (one device on the mobile network at a time). The rep understood what I wanted: “You want to keep your existing phone but carry iPhone once in a while?” Exactly. “I can’t do that.” she said. “You can’t use an iPhone rate plan with another phone, and you can’t use another phone’s rate plan on iPhone.” I offered to pay them more money per month, but they turned me down. iPhone really is a game-changer. As soon as you add iPhone data service to an existing rate plan, it wipes out any other data service you have on the account. I learned that on my own. An iPhone SIM only works for voice in another phone. Software Development