If you text, you've probably gotten text spam. Mine seem to come in the middle of the night, or right before my alarm goes off. And the number of these annoyances has tripled in the last year -- to 45 million text spams a day, according to the security firm Cloudmark.

Nilesh Bhandari is a researcher at Cisco Security. He says one reason for the increase, “more and more people are checking text messages on their phone, often unsure of where these messages are coming from and responding to them quickly.” We all just need to be more careful. “It was the same way in the early days of email,” Bhandari says. “Over time the same sort of trends which causes now folks to be very cautious about email if they don't know who the sender is, I think we're going to see a similar trend happen in the mobile phone environment as well.”

The scammers are following traffic, says Mary Landesman, a researcher at Cloudmark. “The scammers are smart, as long as there's a revolving pool of new users, you know, anybody can get scammed once.” And some spam texts are hard to spot as spam. Say you get one from your bank... or is it a spammer pretending to be your bank? The best choice, Landesman says, is to call and check, “you want to contact your bank via an already-known good number. The same number that you would already contact them by, the same number on your bank statement or the number on the back of your credit card.”

So what about texts which are clearly spam? Landesman says it’s not easy to get off lists, because there aren’t necessarily lists in the first place.

“Scammers will use every possible area code and number combination for a given locale,” she says, “they don't know they have John Smith's number, they just happened to try a number sequence that happens to go to John Smith.”

She says replying “STOP” won’t do any good either. Just like with email spam, responding lets spammers know they have reached a real-live person. Instead, Landesman says, “your best bet is to forward spam to 7726, code for SPAM on old fashioned dial.” That sends it through for an evaluation and helps the phone companies block it in the future. It also gives you something to do, other than tossing your phone across the room.