SIPp (SIP test tool)

SIPp is a test tool / traffic generator for the SIP protocol. It
includes a few basic built-in scenarios (UAC and UAS) and can also
read custom XML scenario files describing arbitrary call flows.

It supports UDP, TCP, TLS, SIP authentication, RTP replay, and many
more features.  For more information, see the documentation from:
    sipp -h
and the SIPp homepage:
    http://sipp.sourceforge.net/