...Sipscan is a fast scanner for SIP services that uses multithread. Sipscan can check several IPs and port ranges and it can work over UDP or TCP. Sipexten identifies extensions on a SIP server. Also tells you if the extension line requires authentication or not. Sipexten can check several IPs and port ranges.
Security tools that can be used to audit SIP based VoIP systems
...The next generation is SIPVicious PRO, a complete new code base and overhaul of the concepts found in SIPVicious OSS. As a toolset it includes more and targets RTC.