ed is also the so-called relational aspect of privacy, i.e., the right to determine, which communications one wishes to receive or not [4]. Communication partners may reasonably expect that their communications and related data will not be used in an unlawful way by third parties. However, not only does SPIT constitute a threat to privacy, the protection against unso- licited communications through the use of various prevention and detection mechanisms raises a lot of questions concerning their compatibility with funda- mental rights. Informational and communicational privacy and confidentiality are relevant with regard to preventing SPIT. Concerns are expressed in partic- ular for existing practices to inspect communications in order to prevent and eliminate spam. Use of detection mechanisms and blocking of incoming calls/ messages can restrict peoples' ability to communicate and therefore be an impair- ment of freedom of speech [4-6] and the right to receive and impart informa- tion, which is also recognized as an integral part of the freedom of information. In this chapter we are discussing SPIT. We provide first a framework to defile and classify SPIT. Then, in Section 19.3, we identify some of the SIP vulnerabilities that might be exploited by potential SPITters. We then stress the criteria that enable any anti-SPIT framework to identify which session and call-establishment attempts should be classified as SPIT. In Section 19.4 we present the results of our survey about the anti-SPIT frameworks already presented in the literature, as well as their classification as prevention, identi- fication or handling approaches. Next we illustrate our proposed quantitative and qualitative criteria for assessment and evaluation of the proposed anti- SPIT frameworks, together with a compliance study. In Section 19.7 we discuss the legal issues pertaining to SPIT detection mechanisms focusing on protec- tion of communications secrecy and privacy. Finally this chapter summarizes its findings and proposals in the correspondi