Researchers enhance spam call filtering

April 3, 2009

Researchers in Helsinki Institute for Information Technology HIIT are developing a new system for filtering spam calls in a flexible way. Spam calls (junk calls or Spam for Internet Telephony, SPIT) are unwanted calls often made by an automat playing a recorded advert.

As free Internet-based telephony is rapidly gaining popularity over traditional charged calls, the risk of spam calls is increasing. Skype is one of the best known providers of free calls using peer-to-peer networks.

HIIT researchers Joakim Koskela, Juho Heikkilä and Andrei Gurtov have created a system for filtering calls on peer-to-peer networks in a more flexible way than before. In the new system, users can accept calls from people who are unknown to the user, but amongst the contacts of friends, or even friends of these contacts. Before the user answers the phone, the system can warn the user that he does not know the calling person.

The flexibility makes spam call prevention more practical. This makes it possible to use the filtering more commonly than today.

The new system can still completely block calls from unknown persons and let friends through, just like Skype today.

Technically speaking, the goal is to implement an application integrating Host Identity Protocol HIP and Peer-to-peer Session Initiation Protocol P2P SIP. The application provides VoIP and IM capabilities using trust chains to prevent spam calls. One of the challenges is to form trust chains from call trace data without violating privacy.

Provided by Helsinki University of Technology