Few tools of modern technology have become as prevalent as the cell phone, which allows you to be in touch (almost) all the time, (almost) anywhere.

And you can do more than just talk–modern phones let you send and receive e-mail and text messages, and even surf the Web. Sifting through the sea of service plans and handsets can be difficult, but we’ll walk you through what you need to know to get the phone and service plan that are right for you.

The Big Picture

Cell phones are more than just convenient communication tools: They allow you to check e-mail, sync with the calendar and contacts on your PC, dial a number by the sound of your voice, read breaking news on the Internet, take photos, play games, send text messages, view and edit documents, listen to music, and more.

But choosing a phone–and the service plan to go with it–requires some legwork.

Your choice of phone may depend on your choice of wireless service provider. If you’re shopping for a carrier, you first need to figure out which carrier offers the best coverage and monthly service plan in your area. Then you’ll have to select a phone from the assortment that your chosen service provider offers. With the exception of a few handsets, most phones work only on one provider’s system because carriers have mutually exclusive networks, and many carriers lock their phones so you can’t take the same phone to another provider.

The third generation of mobile communications technology, commonly called 3G, is becoming more widely available. It’s supposed to boost data-transfer performance to 2 megabits per second from the more common data-transfer rate of 19.2 kilobits per second, and is particularly handy if you use a phone to wirelessly access data such as e-mail, text messages, and the Web.

The availability of 3G service remains a mixed bag.

Sprint and Verizon Wireless use the Evolution Data Optimized (EvDO) network, which offers average download speeds of 400 to 700 kbps and potential maximum download speeds of 2 mbps. AT&T and T-Mobile support a 3G network called HSDPA (High Speed Downlink Packet Access), which is available only on select handsets. (AT&T’s HSDPA is also available for use with PC Cards.) HSDPA promises average download data rates of 400 to 700 kbps with bursts to more than 1 mbps. While more phones are offering support for HSDPA, most AT&T and T-Mobile phones still support EDGE (Enhanced Data rates for Global Evolution), which promises data transmission speeds of 384 kbps, and GPRS (General Packet Radio Service), with an average speed of 40 kbps but the capability to go up to 115 kbps.

Key Phone Features

Wireless standard: World travelers are more affected by wireless standards than are users based strictly in the United States. Most of the world uses networks based on the GSM (Global System for Mobile communications) standard. U.S. carriers, however, use a variety of networks in addition to GSM. U.S. carriers work on the CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), iDEN (Integrated Digital Enhanced Network), AMPS (Advanced Mobile Phone Service), GPRS (General Packet Radio Service), EDGE (Enhanced Data rates for Global Evolution), and/or EvDO (Evolution Data Optimized) standards. AT&T runs on the AMPS, EDGE, GSM, GPRS, and TDMA networks. Sprint Nextel uses the iDEN network exclusively. Sprint and Verizon Wireless run on CDMA and EvDO; Verizon also uses AMPS. T-Mobile supports GSM and GPRS networks. It is important to note that while AT&T runs on both GSM and TDMA networks, the services and the phones that use them do not interoperate.

Band support: The more radio bands a phone supports, the more frequencies it picks up. Quad-band phones, as their name suggests, operate across four frequency bands. Theoretically, they provide better coverage than triple-, dual-, or single-band phones. These so-called world phones are compatible with four GSM frequencies–850 MHz (prevalent in the United States), 900 MHz (prevalent in Europe), 1800 MHz (prevalent in Asia), and 1900 MHz (also available in the U.S.). As a result, they function around the globe. You can also find tri-mode phones that work on two digital frequency bands in addition to an analog network, a particularly handy feature if you travel to rural areas.

Design: You can choose among flip-open, clamshell-style phones; nonflip, candy bar-style phones; slider-style phones that–obviously–slide open; and swivel phones that twist open. Low-end flip phones may lack a separate caller ID screen, but many new phones sport dual screens–a small, external LCD on the cover plus an internal display. If you buy a nonflip phone, make sure it has a keypad lock that prevents inadvertent dialing–a helpful feature when you put the phone in a pocket or bag.

Whichever type of phone you choose, check its ergonomics. Is it comfortable against your ear, and can you hear callers without constant adjustment? Can you use the phone with one hand? Consider hands-free use: Can you comfortably hold the phone to your ear by scrunching your neck and shoulder? Also, look for the placement of the headset jack–a jack located on top of the phone is often more convenient than one located on the side.

Size and weight: Part of what makes a phone easy to use is its portability. A typical standard cell phone weighs about 4 ounces, and most nonflip models are about the size of an energy bar–approximately 5 inches long, 2 inches wide, and 1 inch thick. An exception is a smart phone with a full QWERTY keyboard, such as a Palm Treo or BlackBerry device. Though these hybrid units continue to get smaller and slimmer, they are larger than a basic cell phone, and you should keep that in mind if you plan to use one for long phone calls.

Battery life: Most new phones allow at least 4 hours of talk time and 2 to 6 days on standby. Some phones can last up to 14 days or more on standby. Keep in mind that several factors affect battery life; high-speed 3G networks tend to be power-hungry, for example, and the phones that support them often have shorter battery life.

The signal strength of your cellular service also has an effect, since a phone that constantly searches for signals will run itself down quickly. Depending on the phone, recharging the battery should take about an hour or longer. When you buy a phone, consider optional accessories such as a higher-capacity battery and a portable charging adapter for use in a car.

Screen: If you intend to send and receive text messages, surf the Web, or use the phone’s organizer, make sure the screen is up to snuff. Make sure it’s big enough for you to take full advantage of the phone’s features. If you’re going to surf the Web or edit office documents on your phone, a screen that’s less than 2 inches diagonally will feel very small.

The screen’s contrast and backlight strengths are also important. The phones we’ve seen show marked differences in viewing quality. If your phone allows you to adjust such settings, you can make text and graphics easily viewable–even in bright places. These days, most phones offer color screens, which are easy on the eyes.

When the first-generation iPhone launched in 2007, it touched off a touch-screen frenzy. Since then, more and more phones have come out with touch screens. If you’re looking for such a phone, keep in mind that not all touch screens are created equal. Some–like the iPhone’s screen–support multitouch, which means they can register more than one touch point at a time. This technology allows you to pinch and grab the screen to zoom