(MONEY Magazine) – If you have the sort of friends I do (the sort who forward really important e-mails), chances are you've recently gotten a message that read: "In a few weeks, cell-phone numbers are being released to telemarketing companies, and you might receive sales calls on cell phones." That e-mail has shown up in my inbox several times. And I have to admit, the thought of telemarketers calling my mobile is extremely distressing.

Fortunately, this e-mail is more urban myth than reality. A national cellphone directory is, in fact, on the way. But that doesn't mean you'll be listed. And while telemarketers can call your cell phone, you can protect yourself.

THE 411 ON 411. Starting this spring, you'll be able to call 411 for a wireless number just as you would for a landline. All but one of the major cell-phone carriers—Alltel, Cingular/AT&T, Nextel, Sprint and T-Mobile, but not Verizon—are participating in the directory, which will be run by database company Qsent. Once the service goes live, your wireless provider may ask if you want to list your number. You must opt in. If you say no or simply do nothing, your number will be unlisted. If you say yes and later change your mind, you can have your number removed within a few days, at no cost.

What should keep telemarketers at bay is that Qsent has agreed not to sell the list. And the company isn't planning to publish an Internet-based directory or a phone book, which will also thwart telemarketers. For a telemarketer to get your number from the directory, the company would have to call 411 just like the rest of us. At 50¢ to $1 a call, plus the salaries of workers placing such calls, the cost is simply prohibitive. "By the time they're through, they could spend $5 to $10 getting a single number," says Greg Keene, chief privacy officer for Qsent.

BLOCK THAT CALL. Before you rest easy, consider that a telemarketer can still get your cell-phone number—probably because you gave it to someone who sold it to a listing company that sold it to a telemarketer. Someone like—believe it or not—your pizza delivery joint.

To protect yourself, don't give out your cell-phone number when another number would do. And by all means, register your wireless phone (as well as your landline) at donotcall.gov. Then if a telemarketer calls you more than 31 days later, you can complain to the Federal Trade Commission at ftc.gov (infractions cost telemarketers up to $11,000).

WHO WANTS THIS? Still, you have to wonder (at least I wonder) why anyone would ever want to list his wireless number, especially since incoming calls count against your monthly minutes. In a recent survey by the Pierz Group, a telecommunications consulting firm, 90% of mobile subscribers said they would not want their cell number listed the way their home phone numbers are. Even with protections—no published or Internet directory, no list selling—only 53% would list their number.

Initially the people most likely to use the directory are doctors, lawyers and small business owners, not consumers, says Joe Bradshaw of WirelessAdvisor.com. These groups want customers to find them at any cost.

In the not-too-distant future, thanks to better technology, more consumers may want to list their number. Soon you'll be able to program your phone so that only a certain set of numbers can get through 24 hours a day; a larger group will be able to call from, say, 9 to 5; and too bad for everyone else. When that happens, you may very well decide it's handy to list your number in case, for example, your boss forgets it. Personally, I'll pass. I know my boss would never forget my number. But if he does, e-mail works 24/7.