GSM & CDMA

    * These appealing acronyms stand for: Code-Division Multiple Access vs. Global System for Mobile Communications. Did You Know: CDMA technology was used to thwart German communications jamming during WW2. Good trivia for cocktail party chatter.
    * For the North American consumer, this essentially boils down to Cingular/T-Mobile (GSM) vs. Sprint/Nextel/Verizon/Alltel (CDMA) For non-U.S. customers, GSM is more or less universal.
    * GSM takes a SIM card; CDMA is tied to the phone. This doesn't really matter all that much, the "user experience," as they say, is essentially the same – unless you travel overseas. GSM is the de facto standard in Asia and Europe. Your CDMA phone will be all but useless. At any rate, if travel overseas is not an issue, it doesn’t matter.

Frequencies

    * With CDMA, it doesn’t really matter. You didn't ask, but I'm telling you anyway: CDMA does not assign specific frequencies -- instead, every channel uses the full available spectrum, and transmissions are encoded with a pseudo-random digital sequence.
    * With GSM, you want to look for 850MHz and 1900MHz frequencies in the U.S.; 900 and 1800MHz overseas.
    * In North America, 850MHz is prevalent in remote or rural areas in particular. Definitely confirm your coverage before buying – that is to say, make sure your phone is going to work where you live.

Having absorbed these technical details, go buy yourself a high-end deli sandwich. As an Informed Consumer, you deserve it.
Locked vs. Unlocked Cell Phones - GSM
This is basically a question of freedom. Unlocked GSM phones let you swap SIM cards -- prepaid, etc. – and there is no contract obligating you to a particular carrier. Locked GSM phones are bound to a particular carrier. It is important to note that with unlocked phones, you will still need to program in your carrier’s Internet settings. It is not that complicated, but it does need to be done. If you don't want to deal with that hassle, then just stick with the locked phone packages for your carrier.
 
If you're shopping from outside the U.S., or plan to use your phone mostly overseas, definitely go with an unlocked phone.
Contract vs. No Contract
The deal here is that the carrier companies actually subsidize the phone manufacturers, thus spawning a subsequent morass of confusing contracts and packages. Carriers and manufacturers are constantly cutting elaborate deals with one another, at an alarming frequency.

Buying a phone without a contract gives you the freedom to choose new plans at will. But it takes more effort to keep on top of things.

When activating, do it over the phone rather than at your local phone retailer. Cell phone carrier shops make money from commissions on new activation. They hate people who buy phones online and will sometimes not activate the handset or manufacture problems. Always call your carrier for activation
Data Phones/Smartphones - Do You Need One?
The first question here – and you'll need to take a hard, unflinching look at yourself – is simple: Are you an e-mail geek? If yes, then get a smartphone. Smartphones are designed handle e-mail as efficiently as current technology allows. If not, a regular will do.

If you're one of those very busy, hyperorganized perople, you'll want superior synchronization features with your smartphone. In this case, Treos and Windows Mobile phones are excellent. Also, RIM Blackberries are pretty good

For pure e-mail awesomeness, nothing beats a Blackberry.  There's a reason they call them Crackberry – they do what they do awfully well, and they do just about everything that can be done on a handheld wireless device.
Data Speed
EDGE, EV-DO, UMTS, HSDPA. What does it all mean? It means more impressive acronyms to throw around at parties!

Basically, this is about network speeds. On a data phone, 3G wirelessly approximates landline DSL speeds. Edge and the others are about one-half DSL speeds.

Unless using your phone as a modem, any speed is fine for e-mail. In general, you want 2G (Edge, EV-DO) or 3G for a modem, otherwise it’s deadly slow. However, if you’re this geeky, you really should just have a smartphone or Blackberry, anyway.

Finally, and we cannot stress this enough, make sure to check on your data plan with your carrier. These can get unnervingly pricey. I forgot to pay my bill once back in the fall of 2006, and somehow managed to collapse the entire Uruguayan economy.
Bells, Whistles, and Advanced Gadgetry

    * Camera. Both still image and short-duration video capture cameras are pretty standard now, and their prevalence has a direct inverse proportion to privacy issues. Thanks to cell phone cameras, everyone is now potentially on camera all the time! Enjoy the sensation of creeping paranoia, everyone! Quality is what you’d expect for something so small. One MP (megapixel) is common now; 2 MP coming on the scene. These resolutions are really only good for digital posting – emails or Web sites – and not for printing. Just to clarify here: 2MP is good for 4x6 pictures, but below that is really just for web or phone resolution…
    * Video Playback. Popular on Verizon in particular, but other carriers as well. You can watch TV, stored video files, even YouTube. It’s incredibly cool, if -- you know – you're cool with the existential ennui that comes with watching TV on your phone.
    * MP3 Player. These are also becoming much more common. Most play pretty well, but features are quite limited compared to a dedicated digital audio player.
    * Expandability. Most recent generation smartphones have removable flash memory cards – typically mini or microSD. You'll need this for MP3 capability. It's not technically required, but you'll want a card if you plan to keep more than a handful of audio files.  (not required, but necessary if you want more than 4 songs or so….
    * Cool Apps. For phones with browsers (almost every phone, nowadays), make sure to download Google Maps. It’s a must-have application, and very possibly the coolest thing you've ever seen in your entire life. Compatibility varies.