What is "warvox"

WarVOX is a free, open-source VOIP-based war dialing tool for exploring, classifying, and auditing phone systems. WarVOX processes audio from each call by using signal processing techniques and without the need of modems. WarVOX uses VoIP providers over the Internet instead of modems used by other war dialers. It compares the pauses between words to identify numbers using particular voicemail systems.

WarVox was merged into the Metasploit Project in August 2011.