http://ucsniff.sourceforge.net/
UCSniff is a VoIP/UC Sniffer / Assessment / Pentest tool with some useful new features, such as IP Video Sniffing. UCSniff is a Proof of Concept tool to demonstrate the risk of unauthorized VoIP eavesdropping on voice and video - it can help you understand who can eavesdrop, and from what parts of your network. It is intended for next generation enterprise VoIP/UC Infrastructures that rely on Voice VLANs to segment UC applications for QoS requirements. UCSniff was born from pentesting and the "VoIP Hopper" tool as an idea to combine automated Voice VLAN Discovery and VLAN Hop with MitM, along with targeted VoIP attacks against users in the VoIP Corporate Directory. Eavesdropping is one of many potential VoIP-specific attacks that can take place, and UCSniff can be used by other researchers and security professionals as a base tool to explore this idea. UCSniff is a text-only application, written in C, that runs in the Linux OS environment. It is freely available under the GPLv3 license for anyone to download and use.