A Phased Framework for Countering VoIP SPAM
VoIP spam will become severe problem preventing from generalization of VoIP service. For the purpose of presenting multi-leveled anti-spit framework, they divided VoIP service domain into three independent domains as an outbound, an intermediary, and an inbound domain. The proposed framework enables administrator to establish anti-spit policies in each domain. In outbound domain, the framework focuses on detecting and preventing spammers. The focus in intermediary domain is to block forged SIP message using sender policy framework. The framework enables victims to directly report spam contents they received to administrator. They showed that the multi-leveled anti-spit framework is enough to mitigate spam attacks.