Robocalls, or automated spam phone calls, are a uniquely modern annoyance. They seemingly serve no purpose other than to annoy and deceive, and are as unsettling as they are transparent.
These automated calls come in a variety of forms. Some tell the recipient that they owe thousands of dollars to some anonymous entity. Others ask for social security numbers and other sensitive information under the guise of government agencies. Meanwhile, a significant portion of robocalls include no audio or message at all and simply hang up as soon as someone answers the call.
Now, a new study from North Carolina State University has investigated several prevailing beliefs or myths regarding robocalls and come to quite a few interesting conclusions. First off, and rather surprisingly, researchers say that robocalls haven’t become more prevalent over the past year or so.
“One of our research questions was whether robocalls were getting worse, or becoming more frequent,” says first study author Sathvik Prasad, a Ph.D. student at NC State, in a university release. “We found that the answer is no – the number of robocalls was virtually identical from month to month.”
Additionally, they also found no evidence to support the popular myth that answering one robocall invites a lot more. The team at NCSU says answering one robocall won’t increase your chances of getting more spam calls.
“We were also curious about whether answering a robocall made it more likely that a phone line would receive additional robocalls,” explains study co-author Brad Reaves, an assistant professor of computer science at NC State. “For years, messaging from government agencies and trusted nonprofit organizations has focused on reducing robocalls by not answering calls from unknown numbers. And while we encourage people to avoid engaging with robocalls, we found that answering a robocall has no effect on the number of robocalls you receive.”
One myth that did prove to be accurate, however, is the almost urban legend at this point of someone’s phone being constantly spammed by hundreds of random calls per day. While rare, this can and does happen to certain people, the study concludes. This scenario, though, is a side effect of a robocaller disguising themselves with a real person’s phone number.
“Everyone on the research team had heard stories about a friend of a friend of a friend who had gotten so many unsolicited calls that they couldn’t even use their phone for a day or two,” professor Reaves says. “And we found that this is a rare, but real, phenomenon. We dubbed these high call-volume events ‘storms,’ and found that they happen when a robocaller identifies itself using a fake phone number – and that phone number actually belongs to someone else. If the robocaller makes hundreds of thousands of calls using the fake number, hundreds of people see it on their ‘missed calls’ list and call it back. The high volume of calls essentially makes it impossible for the person who actually has the relevant phone number to use their phone. However, because robocallers switch numbers fairly often, the inconvenience usually only lasts for a day or two.”
For this research, the study’s authors collaborated with the communications company Bandwidth Inc. to set up 66,606 new phone lines that were used only for robocall monitoring. All those phone lines were monitored and tracked for 11 months in total (early 2019-early 2020).
Over that period, 1,481,201 unsolicited calls were received and 146,000 of those calls were answered, recorded, and analyzed via an automated system (ironically).
“These findings stem from a broader study that is the first step toward a more robust set of tools for reducing robocalls, if not eliminating them,” professor Reaves comments. “We made some fundamental advances in tracking robocalls back to their source, and upended a lot of the conventional wisdom regarding robocalls.”
Besides the findings already mentioned, the research team’s investigation also revealed that roughly 62% of the calls their system received included no audio at all. Moreover, only 38% of recorded spam calls even included enough audio to facilitate a full assessment.
Of course, what about perhaps the biggest question of all when it comes to robocalls: where are all of these spam recordings coming from? Somewhat predictably, the research team says that many robocalls can be traced back to a single “campaign.” After eliminating recorded robocalls that lacked any audio, researchers were able to identify 2,687 separate campaigns by grouping robocalls together based on similar or identical messages/scams/tactics.
“Most of the campaigns only made a few calls, but a handful of those campaigns made thousands of calls. So, effectively you can narrow down a big chunk of robocalls to only a few campaigns. And you can track those down. That’s a subject we’ll be discussing at greater length in the future,” professor Reaves concludes.
The full study can be found here. This research was also presented earlier this month at the USENIX Security Symposium, where it received the first place Internet Defense Prize from Facebook, as well as a Distinguished Paper award.