San Francisco resident Bridget S. (she asked that her last name not be used) nearly fell out of her chair when she opened her T-Mobile wireless bill a few months ago and learned that she owed the company nearly $800\u2014about 16 times her usual charge. "I couldn't believe it. I was just shocked," she told me. \n\nA recent survey by the FCC found that about one in six cell phone users has experienced what the agency appropriately enough calls "bill shock," an unexpected spike in a monthly bill unrelated to a change in contract or service. [For more money-saving tips, see CIO.com's recent article Sneaky Fees: Hidden Charges Add Up for Tech Users. ]In Bridget's case, an illness and some other personal matters caused her to spend a lot of time on the phone with family and friends. She concedes that she probably did make the calls, but wonders why T-Mobile didn't tell her that she was exceeding her monthly allotment. FCC Hears More GripesThe FCC has been wondering about that issue as well\u2014and is considering rules that would force wireless providers to notify customers when they start to run out of voice or data minutes. "We are hearing from consumers about unpleasant surprises on their bills," Joel Gurin, FCC Chief of the Consumer and Governmental Affairs Bureau said in a press release last month. "This is an avoidable problem. Avoiding bill shock is good for consumers and ultimately good business for wireless carriers as well." \n\nOne obvious solution to bill shock would be an alert from the provider when customers get close to their monthly limits. But the FCC survey found that no more than 16 percent of those bill-shocked consumers got a heads up when the usage meter redlined. \n\nWhen I asked T-Mobile about this issue, all I got back was a suggestion that its customers use the company's free service that sends them a text message detailing how many minutes of their allotment remain and how much money they owe. \n\nThat's better than nothing, I guess, and I'll admit that consumers have a responsibility to keep track of their minutes, just as they should keep track of their credit card purchases. But that's not always easy, and it's hard to believe that the wireless companies don't have an ulterior motive here: You guessed it, more money. Big Penalties Per MinuteAccording to Consumer Reports, consumers pay 35 cents to 45 cents a minute for minutes over their allotment, compared to an average base charge of six cents a minute, an increase of up to 650 percent. That explains why 23 percent of the consumers who experience a sudden spike in their wireless bill said the increase was $100 or more. \n\nIt certainly appears that there's no technical obstacle in the way of sending warnings. U.S. Cellular, the no. 5 carrier, already does it, and AT&T, which just ended its unlimited data plans for new customers, will be sending notifications to customers approaching the limit. But on the voice side, neither AT&T nor its largest competitors, Sprint, Verizon and T-Mobile, deigns to do so. \n\nFor the record, both AT&T and Sprint have stated publicly that only a small percentage of their customers run over their voice limits, a statement at odds with the conclusion of the FCC's study. Tips: Avoid Bill ShockMaybe the FCC will force the carriers to send warnings to consumers or maybe the carriers will do it on their own. But until they do, you can and should protect yourself. Here are five tips to help you stop wireless bill pain before it starts. \n\n1.\tCheck your minutes now and then by using the carrier's codes: T-Mobile customers, for example, can find out how many minutes they've used by dialing #646# and then pressing send. For the iPhone, tap *646# and you'll get a text message containing the information in a few seconds. Other bill-related services for the iPhone can be found under '"settings" "iPhone" "AT&T Services." \n2.\tPageonce offers a free "personal assistant" application that tracks cell phone minutes for users of iPhones, BlackBerries, Android and Window Mobile devices. \n3.\tBe aware of what your contract allows and if you consistently exceed your allotment of minutes, consider stepping up to the next tier. But don't do that until you see a pattern; one month of overcharges could be simply an anomaly. \n4.\tIf you do get a huge bill, negotiate, negotiate, and negotiate. Look over the bill carefully, and see if you really did make those calls. Carriers are often willing to work with a customer, especially if he or she threatens to sign up another company. \n5.\tIf you, or more likely a teen-aged offspring, simply can't control how much you talk, switch to an unlimited plan. Some of the smaller carriers such as Metro PCS are quite affordable, thought you won't have as many features. \n\nSan Francisco journalist Bill Snyder writes frequently about business and technology. He welcomes your comments and suggestions. Reach him at firstname.lastname@example.org. \n\nFollow everything from CIO.com on Twitter @CIOonline.