1. Look out for weak signals and dead zones.

Despite improved cellphone technology, weak signals and dead zones are still fairly common. Rural areas have it the worst, but even big cities can experience service issues if there is a concentrated number of cellphone users, says Charles Golvin, principal analyst covering the mobile tech sector at Forrester Research, an independent research company.

Dead zones are much less of an issue today than they were four or five years ago, says a spokeman for CTIA-The Wireless Association, an industry group. You can t anticipate how many people will be in a given cell area at one time, and this can change by the second, he adds. Many providers post coverage maps on their web sites.

2. Using your phone abroad could get expensive.

Cellphone service issues don t necessarily stop at our borders. Overseas service is getting better, but there is still much more work to do, says Jeff Kagan, an independent telecom analyst. For your phone to work abroad, it must support the technology of the local operator. What's more, a roaming agreement must exist between your service operator and the operator in the country you re visiting. But international roaming often doesn t come cheap.

T-Mobile customers can typically use their existing phones abroad by activating the company s WorldClass International Roaming feature, says a company spokesperson; roaming fees vary based on the country. In France, you ll pay $1.29 per minute for calls; in China, you ll pay $2.99 per minute. And these fees don t include text messaging. With Sprint, some of its traditional cellphones and smartphones work abroad but on a roaming basis with rates ranging from 59 cents to $5.99 a minute depending on the location. A Sprint rental cell that avoids roaming fees will start at $45 for a week.

3. You can t always depend on your cellphone in an emergency.

One fear with spotty coverage is that a cellphone user who needs to make a 911 call won t be able to get a connection in remote areas. Just as bad, he ll reach a 911 operator, but his or her location information will not be available in the system. So the operator won t be able to automatically determine the caller's vicinity.

The FCC requires carriers to make a mobile phone with GPS chip available to consumers or have the ability to locate a 911 caller via triangulation (using cell towers in the caller's region). The problem, however, is that there isn t a standard technology that every phone and every phone service operators can use, says Allen Nogee, a principal analyst at In-Stat, a market research firm. If you re in an area where your phone s operating technology isn t the predominant version, the operator could have trouble locating you, he says. What s more, though the FCC has introduced standards requiring that mobile phones come equipped with a GPS unit, they are just standards not law. Other FCC standards that carriers be able to locate callers through triangulation -- are problematic, since not all areas have cell towers.

The CTIA says that these issues aren t as pressing as they were in the past because providers have been improving their precise-location technology to locate cellphone users almost immediately.

4. Our bills can include additional fees.

When you sign up for a cellphone service plan, the minimum amount you re told you ll be billed on a monthly basis doesn t necessarily include a variety of fees, including federal and state charges. For example, a fee related to the Federal Universal Service Fund is often added to most cellphone bills; this fee subsidizes cellphone and communications services in rural and high-cost areas as well as at schools, libraries and some health-care providers. Likewise, Sprint collects a fee from Washington-based customers to help defray costs of various state and local regulatory fees, says a company spokesperson.

5. Consumers often run into problems with our smartphones.

The bells and whistles that consumers like in smartphones can also trigger complaints. Smartphone users are 18% more likely to inquire about a problem with their phone than those with traditional cellphones, according to a 2010 study from J.D. Power and Associates.

At times, there are also repair issues, says Kirk Parsons, senior director of wireless services at J.D. Power. These can be slightly more in number than traditional phones in part because smartphones have more features. Problems can include a slow Internet connection, an operating system failure or a system freeze, he says.

But typically, consumer confusion stems from adjusting to a more complex device and less from problems with the phone itself, says Parsons. Consumers who aren t among the comfortably digital should ask for a tutorial at the store where they purchase their smart phone.

6. Our voicemail isn t 100% reliable.

Between July and December 2009, 9% of cellphone complaints were about voicemail, according to a study by J.D. Power and Associates. Often the problem lies with the carriers network software, says Parsons. Unlike old-school landline answering machines that store messages on audiotape, cellular voicemail is kept in cyberspace. In order to reach your phone when you check in, it has to navigate a nationwide web of networks. Most of the time, the system works just fine, but when you re outside of your home region, voicemail can get lost in space.

The procedure a wireless device uses to automatically retrieve voicemails from a network server might not work optimally when it is being used outside of the user s home system, says the CTIA spokesperson.

Carriers work hard to overcome these technical challenges, he says. Still, there are situations when the device might not immediately receive a notice of waiting voicemail.

7. Prepaid plans might not help you save.

Don t want to sign up for a one- or two-year contract? Another option is a prepaid cellphone plan, which lets users pay for service without getting into a contract. These plans can be appealing because of the low costs, but they tend to be better for consumers who aren t too dependent on their cellphones.

That s because when your plan runs out of minutes, the phone could shut off. In other cases, you ll have to renew your minutes every few months in order to hold onto your phone number, says In Stat s Nogee.

8. Texting teens are a revenue source.

Text and picture messaging are the most popular mobile activities for teens, with 70% of them sending and receiving texts on a daily basis, according to a 2009 survey by Forrester. What s more, a recent Pew Research Center Study shows that one-third of teens send more than 100 texts per day.

All together, the trends suggest that texting can quickly add up to big charges. And with most teens on a family wireless plan, that means parents are paying those big charges.

But unlike a few years ago, there s little reason for families to pay exorbitant fees (unless their child is one of those who sends hundreds of texts per day) since unlimited text messaging plans are more widely available, as are family plans where all users are covered by a large pool of text messages. The carriers have done a pretty good job recognizing that this is a pain point for parents, says Golvin.

Of course, another option particularly for those in their late teens is for parents to make them get their own plan and pay their phone bills themselves.

9. Taking your cellphone to another carrier can be tricky.

Not only can you take your cellphone number with you when you switch carriers, you might be able to hold onto your cellphone, depending on the carrier. T-Mobile, for example, will provide you with an unlocked SIM card after 90 days, which allows you to use your phone with another carrier. Sprint may unlock your phone after you ve fulfilled the terms of your contract. And AT&T will do the same with most of its mobile phones.

But before taking your phone to another network, consider the pitfalls. It is never really worth the effort, says Kagan. Even though the device may work on another network, you are always better off getting a phone that has been fine-tuned to work on the network you are using. A Sprint spokesperson says that its handsets may not function properly on a competitor s network regardless of the locking component because each Sprint phone has software and operating systems that work with Sprint's technology and software.

10. Leaving us could cost you.

Many cellphone users, even if they re unhappy with their plan or provider, don t switch services for one simple reason: early termination fees. Ending a contract before it runs out can cost you up to $200 or more, depending on your carrier. Fees will vary based on carrier and your length of time in the contract. With T-Mobile, for example, a $200 fee per line applies if service is canceled during a one- or two-year contract term.

However, since November 2007, T-Mobile has started to prorate early termination fees for new contracts, with the fees declining the further a consumer is into the contract term. A spokesperson says this change has resulted in a more flexible policy for customers entering into a contract agreement with T-Mobile.

At AT&T, the early termination fee can be as high as $175, but for new and renewing wireless customers, it gets lowered by $5 for every month that a subscriber is in the contract. Also, a fee isn t charged if a customer cancels their service within 30 days of activation, says a company spokesperson.