Abstract: Framework for countering VoIP SPAM. The framework is applicable to all sessions sending out the spam from an outbound domain to a inbound domain, in which the outbound domain and the inbound domain respectively has: a spam prevention system for detecting whether an outbound call is spam and blocking the call if needed; a spam prevention policy server for adding, modifying, or deleting spam countering policies being applied to the spam prevention system; and a call server for making or receiving a call, in connection with the spam prevention system.

Abstract: Disclosed are a user agent providing secure VoIP communication and a secure communication method using the same. A user agent of the invention has an additional module for providing a secure function as well as a module for providing general communication, thereby supporting the secure communication. In addition, as a secure communication method using the user agent, a signaling security mechanism negotiation method and a media encryption algorithm negotiation method are provided. Hence, it is possible to provide internet telephone users with a secure VoIP communication service.