MarketWatch

NEW YORK -- Cell phone spam still trails computer spam, with the average cell phone user receiving no more than a few spam text messages per year. But in some ways, it can be even more intrusive, causing your phone to ring or vibrate at inopportune times and cost you money -- 10 cents to 25 cents per message if you don't have a data plan.

Since 2005, the CAN-SPAM Act (Controlling the Assault on Non-Solicited Pornography and Marketing) has prohibited commercial e-mail and text messages to be sent to cell phones without express prior authorization. Unfortunately, the law leaves commercial entities lots of loopholes, including allowing charities and political campaigns to shoot you all the messages they want on your dime.

From Consumer Reports magazine, here are four ideas for what you can do to minimize the chances of getting unwelcome text messages:

Act fast. Call your carrier as soon as you receive a spam message. While no hard-and-fast rules govern the removal of unsolicited text-message charges, you may have more luck having a handful of charges waived than waiting until, say, several dozen have accumulated.

Block cell spam at the source. Virtually all spam messages come over the Internet via a SMSC (Short Message Service Center) or e-mail gateway, often from overseas. Go to your cell account online and access your e-mail and messaging preferences. Then activate the setting that blocks messages over the Internet.

Register your cell number to block spam. You may already have registered your landline with the National Do Not Call Registry (www.donotcall.gov). Using the same Web site, now you can also register your cell number to block telemarketers.

Don't invite more spam. Free or inexpensive ringtones and games from third-party vendors may be tempting. But each such download may unwittingly put you at risk of spam messages or other headaches, such as fraudulent charges and identity theft. The bottom line: as with your computer, never download to your phone anything from a source you don't know and trust.