Here is a handy tool for those with the responsibility of assuring security of a network handling voice and video over IP. UCSniff is a free VoIP and IP video security assessment application that runs on Windows and Linux. It has interesting features, including the targeting and location of VoIP users, verification vulnerability to eavesdropping, and a dozen of others. It also has the ability to record whole voice conversations, which makes it an interesting voice recording tool. UCSniff supports most VoIP codecs and therefore can work in a lot of places and deployments. There is a good overview of the product and the download link on sourcefourge. There is also a set of nice and smart examples of where and how you can use UCSniff, such as locating an IP Phone.
Besides, this weekend, a couple of researchers of Viper Lab at Sipera Systems want to show us that if we use VoIP-based mobile devices over Wi-Fi or over IP video phones, we'd better be careful. At ToorCon this Saturday, UCSniff will be used to demo that a conversation on an iPhone over an unsecured wireless network can be broken into. Read more on that.