Before You Buy a Cell Phone

Locked vs. Unlocked

As mentioned earlier, carriers normally sell GSM handsets locked to keep you from switching services by swapping out the SIM card. But you can buy an unlocked phone from a third party, typically an online store or an eBay vendor. The benefits: No contract is required, and you're free to use any SIM card at any time, including cards from overseas carriers (for more on this option, see "Roam If You Want To: Tips for Globetrotters").

The downside: Unlocked phones are generally expensive. For example, at this writing, in late June, I noticed that several eBay vendors were selling an unlocked version of the BlackBerry Curve 8300 for $450. At the same time, AT&T was offering a locked Deluxe version for just $300 (after a $100 mail-in rebate).

But be sure to shop around--prices will vary. Pricegrabber.com found an unlocked Curve for $400 at Newegg.

Mobile Data

E-mail, messaging, and Web access on a smart phone can be terribly addictive. And unfortunately, like many other addictions, mobile data can get pricey.

Some carriers, most notably AT&T and T-Mobile, charge more for data services that run on PDA phones--Palm Treos, the Samsung Blackjack, the T-Mobile Dash, and the Sidekick--than for those on standard handsets.

Some data plans depend on a particular model. For example, BlackBerrys require a BlackBerry-specific plan to support the push e-mail feature that BlackBerrys are known for. Some carriers also charge for the ability to sync corporate e-mail accounts on clients like Outlook and Lotus Notes.

Text and picture messaging, as well as over-the-air music and TV downloads, incur additional charges; check with your carrier if you or a family member intends to use these services. Ask what options are available for transferring images captured with your cell phone to your desktop PC.

If you do plan on heavy data usage, get an unlimited data plan that covers all of the above. Otherwise, you might be quite content with subscribing to the basic data connection and paying for each text message and a megabyte or two of Web surfing each month. You can change your data services if you find you're not using them or need to expand your plan--but you may have to extended your contract if you change its terms.

Like virtually every other aspect of your contract, this point is well worth asking about before you agree to sign on the dotted line.