ohrwurm is a small and simple RTP fuzzer, it has been tested it on a small number of SIP phones, none of them withstood the fuzzing.

Features:

reads SIP messages to get information of the RTP port numbers
reading SIP can be omitted by providing the RTP port numbers, so that any RTP traffic can be fuzzed
RTCP traffic [...]

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 [...]

Vishing, now there’s a new term for you. Basically its Phishing - but utilising VoIP call services, which makes it very easy to spoof the Caller ID.
Even though Caller ID Spoofing was Made Illegal in the USA - people will still continue to do it, remember the FCC said it’s still easy to spoof caller [...]

SIP devices are getting to be very common now, especially with open source bundled OS offerings like Trixbox making it easy to setup your own digital or IP-PBX.

Along with the frequent installations, many (if not most) VoIP devices have available a Web GUI for their configuration, management, and report generation. These Web GUIs are often [...]

VoIP Hopper is a GPLv3 licensed security tool, written in C, that rapidly runs a VLAN Hop into the Voice VLAN on specific Ethernet switches. VoIP Hopper does this by mimicking the behavior of an IP Phone, in both Cisco and Avaya IP Phone environments.
In Cisco IP Phone networks, it first dissects either [...]

The VoIP Security Alliance (VOIPSA) is pleased to announce the public release of its VoIP security tool list. Check it out at:
http://www.voipsa.org/Resources/tools.php
This VoIP Security Tool List provides categories, descriptions and links to current free and commercial VoIP security tools.

This list was developed to address the current void of VoIP security testing resources and sites, [...]

SIP Proxy is an Open Source VoIP security test tool which has been developed by the students Philipp Haupt and Matthias Halimann during their diploma thesis and second student research project at the University of Applied Sciences Rapperswil.
With SIP Proxy you will have the opportunity to eavesdrop and manipulate SIP traffic. Furthermore, predefined security test [...]