"For example, we have found the SMS trafc volume at cell towers can easily get multiplied by more than 10 times due to the activities of spammers," the researchers say in their paper on the topic. "Therefore, the focus of the SMS spam defense is to control spam numbers as soon as possible before they reach a large number of victims."
The vast majority of spammers -- 95 percent - generate more than five SMS messages per hour, and more than 70 percent send more than 50 per hour. In contrast more than 97 percent of legitimate messages send fewer than 5 messages per hour, the researchers say.
Spamming trafc volume can be 10 times that of normal traffic, and at certain network junctures can account for 80 percent to 90 percent of all SMS traffic, they say.
More than 60 percent of spammers target phone numbers in the area codes of major cities; the rest spread it around, the researchers say.
Tim Greene covers Microsoft and unified communications for Network World and writes the Mostly Microsoft blog. Reach him at email@example.com and follow him on Twitter @Tim_Greene.
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