Even if you don't pay for text messaging, you can still receive unwanted solicitations on your cell phone. From the August 2008 Consumer Reports magazine, here are three tips to prevent that:
Take immediate action. Call your carrier to complain. It might offer a quick fix. Check to ensure your e-mail or messaging settings are at the highest level of protection
Join the National Do Not Call Registry. You can register your cell phone free at www.donotcall.gov.
Beware of downloads. Just as with your computer, some downloads can prove hazardous to your phone's health. Certain ring tones and games from third parties can open you up to increased spam and even identity theft.
Marshall Loeb, MarketWatch