Robocalls slip through smartphone spam filters, but a new generation of deep learning tools promises to tighten the net.

What’s new: Research proposed fresh approaches to thwarting robocalls. Such innovations soon could be deployed in apps, IEEE Spectrum reported.

How it works: RobocallGuard, devised by researchers at Georgia Institute of Technology and University of Georgia, answers the phone and determines whether a call is malicious based on what the caller says. TouchPal, proposed by a team at Shanghai Jiao Tong University, UC Berkeley, and TouchPal Inc., analyzes the call histories of users en masse to identify nuisance calls.

  • RobocallGuard starts by checking the caller ID. It passes along known callers and blocks blacklisted callers. Otherwise, it asks the caller who they are trying to reach and listens to the reply using a neural network that recognizes keywords. If the caller states the user’s name, it passes along the call with a transcript of the interaction generated using Google’s Speech-to-Text API. If not, it disconnects and saves the recording and transcript.
  • TouchPal collected a dataset by enabling users to label incoming calls as harassment, fraud, delivery, sales, and other categories. It used these labels along with information including contacts, anonymized phone numbers, call times, and call durations to train a vanilla neural network to classify nuisance calls before they’re answered.

Behind the news: Many robocallers have outgrown the fixed phone numbers, obviously prerecorded messages, and “press-1” phone trees that were dead giveaways in the past, making it harder for recipients to recognize spam calls even after answering the phone.

  • Some robocallers use personalized audio, often including clips of recorded human voices that play in response to specific keywords, to simulate a human on the other end of the line.
  • Robocallers commonly falsify the number they’re dialing from, making them hard to trace and virtually impossible to block.

Why it matters: Robocallers placed nearly 4 billion nuisance calls in the U.S. in January 2021. These numbers have hardly budged since 2019 despite government efforts to combat them. The problem is even worse elsewhere. In Brazil, the average user of one call-blocking app received more than one spam call daily. It’s unlikely that robocalls will ever disappear entirely, but machine learning could relegate them to the background, like email spam.

We’re thinking: If everybody blocks robocalls, maybe robocallers will start sending nuisance calls to each other.


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