SIPVicious suite is a set of tools that can be used to audit SIP based VoIP systems. It currently consists of four tools:

svmap - this is a sip scanner. Lists SIP devices found on an IP range
svwar - identifies active extensions on a PBX
svcrack - an online password cracker for SIP PBX
svreport - manages sessions and exports reports to various formats
svcrash - attempts to stop unauthorized svwar and svcrack scans

Download
http://code.google.com/p/sipvicious/downloads/list