CallRank - a Novel Approach to SPIT Reduction

Courtesy of the VoIPSec list, I saw this paper proposing a novel approach to the detection of Internet Telephony SPAM (SPIT). In brief, the idea is to detect behavioural differences between legitimate telephone users and spammers, and use this to build a reputation system, presumably real spammers get a steadily worse and worse reputation that will be rewarded by their calls being routinely rejected.

In the words of the paper's authors:

Quote:

This paper proposes CallRank, a novel mechanism built around call duration, to differentiate between a legitimate user and a spammer. Our approach is motivated by the simple bservation that a legitimate user typically makes and receives calls and many of the calls last for significant durations. On the other hand a spammer’s/telemarketer’s goal is to deliver information to as many people as possible by making a large number of relatively brief calls. A spammer will typically receive no calls or a much smaller number of calls. The difference in call patterns is that, for a spammer, the call pattern is largely unidirectional while it is bidirectional for legitimate users. We take advantage of this difference in call patterns and use call duration to create call credentials that callers can provide to call recipients as proof of an implicit level of trust.

The paper by Balasubramaniyan et al can be downloaded here.