A Sentinel to Screen Phone Calls

New software could block voice spam.

A system for automatically screening phone calls has been developed by researchers at Microsoft. It works by analyzing characteristics of a caller's voice and word usage to figure out how urgent a call is and whether the caller is a friend, family member, colleague, or stranger. Then the call can be either put through or sent to voice mail.

Called V-Priorities, the system was originally part of a larger effort to ensure that urgent calls get through when an individual is busy or in a meeting. But, according to Eric Horvitz, a senior researcher at Microsoft Research in Redmond, WA, who created the system, it could also prove to be useful for filtering the growing number of spam phone calls.

In preliminary tests, the prototype system was 90 percent accurate at judging whether or not calls were unsolicited, says Horvitz. Similarly, its ability to judge the personal "closeness" of the caller was 84 percent accurate, while it could distinguish business calls from personal calls 75 percent of the time.

Extracting such information is quite feasible, says Bill Keller, a computer scientist who specializes in natural-language processing at the University of Sussex in England. There's already been progress in using programs to screen automated call-center calls, he says. "They are trying to spot when people are getting agitated." Also Corpora, based outside London, has had some success in analyzing speech for signs of sentiment.

At the moment, voice spam is still relatively rare, says Raimund Genes, chief technology officer of anti-malware at Trend Micro, an anti-virus company in Munich, Germany. But the growing popularity of Voice over Internet Protocol (VoIP) phone calls is likely to increase the amount of such spam because of the reduced cost of making calls, he says.

Furthermore, VoIP doesn't just allow cheaper and easier spamming, it could also make many VoIP-based corporate phone networks more vulnerable to other sorts of attacks, says Scott Sobers, director of the Service Provider Market for IBM Tivoli in Washington, DC. In the future, such networks could be vulnerable to new types of computer viruses and other malicious software, which in theory could be introduced to the network merely by answering a phone, he says.