HD just released WarVox this week the most advanced wardialing tool I have ever seen, here is an excerpt of the introduction:
WarVOX is a suite of tools for exploring, classifying, and auditing telephone systems. Unlike normal wardialing tools, WarVOX works with the actual audio from each call and does not use a modem directly. This model allows WarVOX to find and classify a wide range of interesting lines, including modems, faxes, voice mail boxes, PBXs, loops, dial tones, IVRs, and forwarders. WarVOX provides the unique ability to classify all telephone lines in a given range, not just those connected to modems, allowing for a comprehensive audit of a telephone system.
WarVOX requires no telephony hardware and is massively scalable by leveraging Internet-based VoIP providers. A single instance of WarVOX on a residential broadband connection, with a typical VoIP account, can scan over 1,000 numbers per hour. The speed of WarVOX is limited only by downstream bandwidth and the limitations of the VoIP service. Using two providers with over 40 concurrent lines we have been able to scan entire 10,000 number prefixes within 3 hours.
The resulting call audio can be used to extract a list of modems that can be fed into a standard modem-based wardialing application for fingerprinting and banner collection. One of the great things about the WarVOX model is that once the data has been gathered, it is archived and available for re-analysis as new signatures, plugins, and tools are developed. The current release of WarVOX (1.0.0) is able to automatically detect modems, faxes, silence, voice mail boxes, dial tones, and voices.
It is written in Ruby and it is design to run in modern Linux distribution specifically in Ubuntu 8.10 and Backtrack 4. I will be testing the tool and looking at adding it to my pentesting tool kit.