WarVOX

WarVOX was a free, open-source VOIP-based war dialing tool for exploring, classifying, and auditing phone systems.

[1] WarVOX used VoIP providers over the Internet instead of modems used by other war dialers.

[2] It compared the pauses between words to identify numbers using particular voicemail systems.

[3] WarVox was merged into the Metasploit Project in August 2011.

[4] The WarVOX project is no longer maintained.