What's more annoying than having your e-mail in-box flooded by spam ? How about having your cell phone inundated with unwanted messages that you actually have to pay for.

Wireless spam is starting to appear as text messages on cell phone users' small screens. Like wireless viruses, this nuisance doesn't yet compare to the viruses and unwanted mail that strike PCs, but experts say the problem will escalate quickly.

"The tolerance level is much lower for spam on wireless phones, so this is a problem that will [grow] even faster than e-mail," says Sara Radicati, an analyst with The Radicati Group.

Text-messaging spam is particularly annoying because, per service agreements with their carriers, subscribers likely pay a few cents to receive a text message. And these messages usually cause the phone to beep when they arrive. "It drives me crazy when my BlackBerry's alert goes off and it's junk mail," says Frank Gillman, director of technology with Allen Matkins, who manages at least 250 cell phones for the law firm.

Unlike e-mail spam, there aren't applications on the market to protect users from these messages; because text messages are delivered through the carrier's wireless network, it's up to the carrier to stop spam before it gets to subscribers. Most carriers are taking such steps; Verizon Wireless has spam filters installed on its network and has prosecuted some text-messaging spammers - a step the company believes will act as a deterrent. But given how easy it is to text message people you don't know (a 10-digit cell phone number at the wireless operator's domain, for example 1234567890@operator.com), it isn't hard to believe text messaging could be the next fertile ground for spammers.

Back to feature: "Is your cell phone at risk?"