Do You Live Near a Text-Message Spammer? Check Your Area Code

Photograph by Michael Caronna/Corbis

Of the top 25 area codes where text-message spam originates from the U.S., 15 are in California, Florida and New York.

If you live in the 347, 201 or 510 area codes, or basically anywhere along the eastern edge of Florida, there’s a good chance you live near a mobile-phone spammer or a business that enables one.

According to new research from Cloudmark Inc., a San Francisco-based security company, the bulk of text-message spam in the U.S. comes from just a few regional clusters on the coasts. That’s a twist from traditional e-mail spamming, which often originates outside the U.S.

Of the top 25 area codes where text-message spam comes from the U.S., 15 are in California, Florida and New York. The clustering suggests the criminals live there, do business with companies that are based there, or both, said Rachel Kinoshita, head of Cloudmark’s security operations.

The fact that Cloudmark can even identify where the spam is coming from highlights a key difference between text-message spam and e-mail spam.

Criminals use the infected computers of innocent people to send e-mail spam, which makes it hard to track. But hacking into someone’s cell phone to send mobile spam is more difficult.

So instead, text-message spammers buy lots of prepaid subscriber identification modules, or SIM cards (a key component that cell phones need to make calls). The cards are then put into SIM “boxes” that can hold dozens of the cards. Those boxes, which are testing tools the mobile operators use, get the cards to behave as if they’re in real phones. Criminals then hook the boxes up to computers that tell the cards to pump out text messages until the accounts are drained.

However, before the cards are sold, they are assigned blocks of numbers based on their geography. This opens the door for tracking.

Mobile operators such as AT&T, Sprint and Verizon Wireless use Cloudmark’s data to disconnect spammers’ numbers, Kinoshita said. Cloudmark says its anti-spam technology helps shield nearly 2 billion people worldwide from attack.

As Bloomberg reported last month, smartphone spamming has now reached 4.5 billion messages a year in the U.S. Kinoshita recommends forwarding any text message spam you get to the short code  “7726,” which spells “spam” on most phones, to alert your network operator to the abuse. That’s an industry-wide initiative that uses Cloudmark technology.

She cautions against responding to the messages, which often promise gift cards or Apple products.

“There’s no free iPad out there for you and there’s no $1,000 gift card,” she said.

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