When Congress passed the CAN-SPAM Act in 2003, it included cell phones by banning the sending of spam e-mail to cell phones. At the time, no one contemplated the phenomenal growth of Short Message Service text messaging, or SMS. By 2007, more than 1.1 million wireless spam text messages were delivered in the United States.

Hoping to curb that trend, Sens. Olympia J. Snowe (R-Maine) and Bill Nelson (D-Fla.) have introduced legislation that would strictly prohibit commercial text messages to wireless numbers listed in the Federal Trade Commission's Do Not Call registry.

"Mobile spam invades both a consumer's cell phone and monthly bill," Snowe said in a joint statement with Nelson. Snowe added that mobile spam text messages often contain viruses and malicious spyware.

"This significant and looming threat must be addressed in order to protect consumers and vital wireless services," Snowe said.

Mobile spam jumped 38 percent from 2006 to 2007 and similar increases are expected in the future. Moreover, spam text messages cost consumers money: Wireless subscribers typically are charged for receiving text messages as well as sending them, sometimes as much as 20 cents per message.

"Spam e-mail is bad enough," Nelson said. "Now, we are seeing a proliferation of unwanted text messages—and consumers are getting stuck paying."