I know that in ZRTP, the negotiation of the cryptographic keys takes place entirely in the RTP stream. However, I do not understand: 1. How can this be proven when having setup FreeSWITCH and having deployed ZRTP, and having two softphones (such as X-LITE) connected in a test environment. Can a tool cush as Wireshark or any other be used in this case? 2. What are other protection mechanisms provided to prevent third-parties from masquerading as one of the end-points? Thank you! Serge. _________________________________________________________________ The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=PID28...