SIP Parsers and Stacks

RADVISION's SIP Toolkit is a powerful and highly versatile set of tools designed to address the development requirements of a broad range of SIP-based products from high-end SIP systems, such as softswitches and SIP proxy servers, to compact embedded devices, such as cellular phones and PDAs.

eXosip is a library that hides the complexity of using the SIP protocol for mutlimedia session establishement.

NIST SIP - An IP Telephony project running at the National Institute of Standards Technology has made a SIP parser in Java (based on Antlr) available in the public domain.

RTP Tools - consists of a number of small applications that can be used for processing RTP data.

sipXtest - sipX Family of ProjectsThe sipX family of projects were contributed to SIPfoundry by Pingtel Corp.. They are now open source projects available for use by anyone.

SIP Scenario Generator - The SIP Scenario Generator creates SIP Call Flows or SIP scenario diagrams, in html format, of SIP messages from ethernet capture files.

minisip - libmsip - libmsip is a C++ library that implements the IETF work-in-progress SIP protocol.

TransNexus OSP Toolkit is free source code for a complete OSP client protocol stack. The Open Settlement Protocol can be used by policy server to enforce secure interdomain call authorization among SIP networks.

Vovida provide a number of open source protocol stacks for the Linux platform, including a SIP one.

Windows Real-Time Communications Client API SDK v1.2
The Microsoft® Windows Real-Time Communications Software Development Kit v1.2 (SDK) provides the ability to create applications that integrate audio, video, data collaboration, instant messaging, and presence using the standard Session Initiation Protocol (SIP).

See also:

+ Codecs 
+ Developers Programs and Community sites 
+
Free SIP and ENUM Services 
+ Commercial Service Providers
+ SIP Parsers and Stacks 
+ Other Stacks, RTP Applications, code and bits and pieces
+ SIP and DNS
+ Testing Tools 
+ Robustness testing 
+ SIP Client Software, User Agents, Source Code
+ SIP Servers, Proxys and Gateways 
+ SIP Drafts and RFC's
+ SIP Center links pages
+ Commercial SIP Products & Service Providers