It started slowly, back in the eighties. Every couple of blocks, someone would come striding along, cell phone pressed to his or her ear, engrossed in conversation. "Self-important geek," I thought to myself--until I became one myself a few years later. And the trend continues: According to the Cellular Telecommunications & Internet Association, more than 38 percent of the people in the United States now own a wireless phone, with more than 65,000 newcomers signing up for service every day.

The only thing more widespread than the tiny devices are the ads for wireless service. You can't turn on the TV without being barraged with promises of ever-expanding digital networks, anytime minutes, and global roaming. If you believe the advertisements, making a stock trade or wishing Mom a happy birthday is just a matter of pushing a few buttons, whether you're attending a meeting in Manhattan or ice fishing in the Alaskan tundra. And the cost of those calls? Hardly worth mentioning.

But as with most things technological, it's not always that simple. If you've spent any time recently researching plans for wireless phone service, you know how bewildering it can be: How many minutes do you need? Are prepaid plans worth considering? How far does your calling area extend? And how high are those roaming charges? Here's how to avoid some budget-busting pitfalls in choosing a wireless phone service provider--and what to do if you're already stuck with a crummy contract.

Shop for a Plan, Not a Phone

Many service providers offer generous discounts on phones when you buy their service, but do the math before you commit. A free phone might be tempting, but chances are it's no great deal in the long run. The phones the providers offer for free generally cost them very little. In exchange for the phone, many plans lock you into a long-term contract--two years or more--at a higher monthly rate than you could get elsewhere if you were willing to kick in some dollars toward the phone. If you try to cancel the contract or switch plans, you could be facing a fee of anywhere from $100 to $400.

On top of that, free or discounted telephones don't always have the features that you need. If you travel frequently, for instance, you will probably want a tri-mode phone, which can shift among analog cellular and two frequencies of digital calling. International travelers should consider looking for a phone that can use Global System for Mobile communication (GSM), the mobile phone system that dominates Europe and other parts of the world.

The bottom line? Shop first for the service plan you need. Rates are likely to continue to drop, so try to keep your contract short. Then look for the best deal you can get on the phone.

Know Your Calling Area

Service can be unreliable, with dropped calls and connections that make it sound like the other party is gargling in a tin can. How can you avoid these wireless pitfalls?

For starters, don't assume the calling area map from the service provider is entirely accurate. "Maps really only show a best-case view," says Joseph Bradshaw, general manager of WirelessAdvisor.com, a Web site that helps consumers find wireless service providers. "The best way to [check local coverage] is to ask around."

Ask friends about their experience with the provider in your home calling area. At WirelessAdvisor.com, you can post questions for users of local providers. Also, ask providers to let you test their service. If you leave ID, many will lend you a phone to make calls in your favorite haunts.

Wireless phone service plans generally require you to sign a contract--typically, a year's commitment--in exchange for access to their networks, a free or discounted phone, and whatever additional features and promotions the providers include. As with any contract, read the fine print. Wireless providers don't like to lose customers, and most impose a steep fee for canceling service early. You may also be required to return your phone. So before signing on, understand the implications of opting out before the contract expires. Confirm that the contract reflects any promises made by cellular service salespeople.

If you're already stuck with a contract you don't like, ask your provider about alternative plans. Service plans are constantly changing (and rates are dropping), and your provider may work with you to find a plan that better meets your needs.

If the idea of being locked into a contract makes you squeamish, consider a prepaid plan, which provides a set number of minutes for a flat fee paid up-front. Prepaid plans are usually more expensive and less flexible than other types of plans. But they can be a good alternative for students or folks with less-than-stellar credit, since they don't require a credit check.

If there's one speed-dial number worth programming on your wireless phone, it's the one that tells you how many minutes you've used each month. Once you exceed your monthly allotment, you'll pay. And pay. Some wireless providers charge 40 cents or more for each minute over your allotment. Those charges add up fast. So before you choose a plan, figure out how much time you're likely to use every month. Estimate high.

Another expense that can add up fast is roaming charges--the extra fee you pay for each minute you're outside your provider's coverage zone. That could just be while you're visiting a neighboring town. Although some plans don't bill you for roaming, most of them do, and the charge is usually levied on top of long-distance fees. Roaming charges can be steep--as much as 70 cents a minute--so be sure to check your home coverage area carefully to ensure that it corresponds with your most frequent calling areas. If you travel a lot, look for a plan with free roaming.

You will want to keep a number of other bill boosters in mind as well. Most wireless providers round each call up to the next whole minute, even if you connect for only a few seconds. Also, unlike with landline service, you may be charged for busy signals and unanswered calls if you stay connected for more than a few seconds.

Watch for Hidden Charges

Toll-free numbers aren't free in the wireless world, either. And don't forget that you pay for incoming calls, though many plans offer the first incoming minute for free. Finally, before you sign on the dotted line, check the plan's activation fee and factor it in over a year's time. A low monthly rate could be offset by a high activation fee, steep long distance and roaming rates, or fees for features such as call waiting and voice mail.

Sorting through the plethora of wireless phone plans and options can make you wistful for the days of rotary dials and party lines. But some great deals are out there. If you do your homework thoroughly, you can end up with one.