reSIProcate is a high performance, object-oriented, C++ sip stack that is compliant with RFC 3261. It includes support for a wide variety of operating systems, including Windows and Linux. It has full support for UDP, TCP, and TLS transports on both IPv4 and IPv6. It also implements the full set of specifications for DNS usage in SIP, including NAPTR and SRV lookups (RFCs: 3263, 2915, 2782) using an asynchronous DNS library (ares).