The IETF is actively working on new standards for SIP security, that will ensure VoIP communications solutions will not be troubled by the flaws of spam and Denial of Service attacks. It may just also be the model for voice migrating beyond the PSTN model and into a new era.

Dr. Cullen Jennings is a Distinguished Engineer in the Voice Technology Group at Cisco. Cullen came to Cisco from Vovida Networks which developed an open-source toolkit for Voice-over-IP. He is also an author of O'Reilly's title "Practical VoIP" and the co-chair of the IETF IPTEL Working Group. Currently Cullen is focusing on conferencing, security, and firewall and NAT traversal. Still active in the SIP and open source communities,
Cullen recently contributed a prototype Instant Messaging and Presence client which integrates strong end-to-end security.