SIPp is a free Open Source test tool / traffic generator for the SIP protocol. It includes a few basic SipStone user agent scenarios (UAC and UAS) and establishes and releases multiple calls with the INVITE and BYE methods. It can also reads custom XML scenario files describing from very simple to complex call flows.
SIPVicious
SIPVicious suite is a set of tools that can be used to audit SIP based VoIP systems. It currently consists of four tools.
VoIPHopper
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 Cisco, Avaya, Nortel, and Alcatel-Lucent environments.
Xplico
The goal of Xplico is extract from an internet traffic capture the applications data contained. For example, from a pcap file Xplico extracts each email (POP, IMAP, and SMTP protocols), all HTTP contents, each VoIP call (SIP, MGCP, H323), FTP, TFTP, and so on. Xplico is not a network protocol analyzer.
ace-voip
ACE (Automated Corporate Enumerator) is a simple yet powerful VoIP Corporate Directory enumeration tool that mimics the behavior of an IP Phone in order to download the name and extension entries that a given phone can display on its screen interface.