Voice over IP is one of the fastest growing Internet based application in today's networking world. As more and more enterprises are moving towards IP based voice network, security has become an important issue. The type of threats that voice traffic is exposed to is similar to those experienced by normal data traffic. However with voice traffic, the issues are much more complicated. While it is important to protect the voice packets from spoofing and eavesdropping, it is equally important that law enforcement agencies have access to these voice packets. With the recent terrorist attacks and increased threat to national security, law enforcement agencies require the ability to tap voice calls and screen them for information pertaining to national security. With the deployment of security mechanisms like encryption, it is becoming harder for law enforcement agencies to decipher the information hidden in these IP packets related to voice calls. Hence, it is important that the security mechanism used in these voice calls be standardized. This would provide law enforcement agencies easier access to the information during crisis situations. In this paper, the authors propose a new security mechanism that will help law enforcement agencies in gathering information pertaining to national safety. Initial analysis carried out by the authors indicates that the overhead caused by the proposed protocol has a minimal effect on the voice communication performance