The falling cost of text messaging is making mobile-phone users a more attractive target for spammers, according to the GSM Association. To counter this, it wants its mobile-network-operator members to "crowd-source" spam reports from their customers to help them identify and cut off spammers abusing SMS (Short Message Service).

As much as 90 percent of Internet e-mail traffic is spam, according to some reports, up from just 20 percent a decade ago. The proportion of spam in mobile text messages is far lower, under 10 percent in the U.S. and the U.K., rising to 20 percent in some Asian countries, according to Brad Greene, vice president of business development at the GSMA.

One thing that has slowed the spread of SMS spam is the cost of text messaging compared to e-mail: Internet spam is profitable even at very low response rates because millions of e-mail messages can be sent for just a few dollars. Now, though, low-cost or unlimited texting plans, and the rising use of high-speed wireless modems, have changed the economics of SMS spam, Greene said in an e-mail response to questions. The GSMA is taking action now to make sure that the Internet spam situation "is not replicated in the mobile world," he said.

In France, operators have been encouraging subscribers to report SMS spam since October 2008. Phone users there can forward offending messages to the Stop-Spam service via the short code 33700. An initial response prompts them to reply with the spammer's phone number, with a final SMS acknowledging the completed spam report. The service has received almost half a million spam reports in this way. This has resulted in the disconnection of only 300 phone numbers for spamming, although many more have received cease-and-desist orders.

The operators can't just block offending SMS messages or shuffle them into a spam folder as many e-mail service providers do. For one thing, the senders have paid for the messages, so the operators are contractually obliged to deliver them unless they can prove that the sender has breached their terms of service, according to a spokeswoman for the Fédération Française des Télécoms. Also, creating an SMS spam folder would mean updating the firmware on millions of phones.

The SMS spam reporting systems in place so far, in France and South Korea, for example, stop at national boundaries, but spam is a global problem requiring a global response, according to the GSMA. In a GSMA study last year, "68 percent of the global mobile network operators surveyed reported receipt of mobile spam originating from senders outside their networks," Greene said.

The GSMA is promoting a system developed by e-mail spam-filtering specialist Cloudmark, which will allow mobile-network operators around the world to pool spam reports from their customers, enabling analysis of the data to determine the sources of attacks and their volumes, said Greene. Armed with that information, they will be able to "curb abuse, pursue enforcement of acceptable use policies and support law enforcement," he said.

The IDG News Service is a Network World affiliate.