Before you switch to the iPhone

Since the iPhone is available only with AT&T, we have little doubt that some eager buyers will be switching carriers just to buy it. If you're one of those people, there are a few points you should consider before making that big purchase on Friday. Remember, you'll be shelling out $500 or more for that shiny new gadget, so you want to make sure you're spending your money wisely.

AT&T coverage
Without a doubt, you better make sure that AT&T has adequate coverage in your area. That would include your home, your workplace, and everywhere in-between. If you don't have an AT&T phone now, try borrowing a friend's or colleague's phone and test in the places you frequent. Keep in mind that reception in buildings can vary, but ultimately you'll want to be able to make and receive calls with few problems. This is an absolutely critical step, unless you want to pay a few hundred dollars for a phone that won't work in your living room.

Porting your number
If you want to transfer your phone number over to AT&T, do not cancel your contract with your current provider. If you do so, you'll lose your number and AT&T will assign you a new one. To keep your number, simply open your new account with AT&T. AT&T will notify your carrier and will transfer the number for you. Just keep in mind that the transfer can take a couple of days.

Carrier termination fee
If you leave your carrier before your contract has ended, you will be stuck with an early-termination fee. These can range from $150 to $200, so be sure to factor that into the price of your iPhone. Verizon Wireless prorates your fee depending on how much time is left on your contract, but not every provider does the same. Be sure to check if yours does.

Pick your plan
Remember you're signing up for a two-year contract, even if you have already switched to AT&T. New customers will have to choose a special iPhone service plan that will be unique to the phone. For $60 a month, you'll get 450 minutes of anytime minutes and 5,000 night and weekend minutes. For $80 a month, you'll get 900 anytime minutes and unlimited nights and weekends. And for $100 a month, you'll get 1,350 anytime minutes and unlimited nights and weekends. All plans will include visual voice mail access, unlimited e-mail and mobile Web surfing, free mobile-to-mobile minutes and 200 text messages a month. And don't forget the $36 activation fee.

Current AT&T customers can add an iPhone data plan to their existing contract for $20 per month, which will give them unlimited data and 200 text messages. More-expensive plans are available as well, and families will have their own options. Try to think carefully beforehand about how many calling and data minutes you'll need. As a general rule, it's better to overestimate your usage rather than underestimating it. You can always adjust your plan later, though that will result in a further extension of your contract. Don't forget taxes and fees either. For a complete list, check out CNET's Quick guide to your cell phone bill.

Find a store
The iPhone will be sold at all Apple stores, but it won't be available at every AT&T location. AT&T franchises won't have it, so you should check before you get in line. AT&T has a handy store locater on its Web site. Also, keep in mind that iPhone goes on sale at 6 p.m., but that stores will vary.

Activation
Apple announced yesterday that you'll be able to activate the phone at home using iTunes, which, incidentally, you'll need an account for if you want to use the iPhone for anything.

Be patient
As the first-generation device, the iPhone will have a break-in period. During that time, there will undoubtedly be some quirks that may be surprising and even frustrating. The touchscreen and the user interface also come with a learning curve, and it doesn't help that the iPhone comes with enormous expectations. Take your time to get to know it, and don't expect too much right away.