Alternative security architecture for IP Telephony based on digital   watermarking
  Problems with securing IP Telephony systems, insufficient standardization and lack of security mechanisms emerged the need for new approaches and solutions. In this paper a new, alternative security architecture for voice-systems is presented. It is based on digital watermarking: a new, flexible and powerful technology that is increasingly gaining more and more attention. Besides known applications e.g. to solve copyright protection problems, we propose to use digital watermarking to secure not only transmitted audio but also signaling protocol that IP Telephony is based on. 
Wojciech Mazurczyk, Zbigniew Kotulski