oSIP is a free softwareVoIP library implementing lower layers of Session Initiation Protocol (SIP) published as rfc3261. The library includes minimal codebase required by any SIP application and offer enough flexibility to implement any SIP extension or behavior. Started in September 2000 and published in April 2001, oSIP is among the oldest SIP open source stack still being developed and maintained. The project was made part of the GNU Project as GNU oSIP in 2002.
"We present results of experiments performed on oSIP, an open-source implementation of the Session Initiation Protocol embedded in many IP Phones."
Association for Computing Machinery. Special Interest Group on Embedded Systems. (2006). EMSOFT 2006: proceedings of the Sixth ACM & IEEE International Conference on Embedded Software. ACM Press. p. 263.
"We applied our tool to a large software application: oSIP, an open-source implementation of the Session Initiation Protocol."
Chakrabarti, Arindam (2007). A Framework for Compositional Design and Analysis of Systems. ProQuest. p. 197.
"The development of m-learning server and user entity will be based on oSIP, eXosip and oRTP, which are open source SIP software."
Li, Frederick; Zhao, Jianmin (2008). Advances in Web Based Learning - ICWL 2008. Springer. p. 545.
"In the second function, they are: the execution of the scripts to switch on/off the wireless interface; the creation and initialization of a new eXosip stack (the C-based SIP stack used by UCT IMS client); and the invocation of a new register phase."
Bonnin, Jean-Marie; Giannelli, Carlo; Magedanz, Thomas (2009). Mobilware 2009. Springer. p. 289.
"The implementation of the client is achieved by the use of several free open-source libraries: the oSIP and eXosip libraries for SIP signalling;..."
Al-Begain, Khalid; Balakrishna, Chitra; Galindo, Luis Angel; Fernandez, David Moro (2009). A Development and Deployment Perspective. John Wiley & Sons. p. 206.
"We have implemented a simple IMS client using eXtended osip (eXosip) library in C programming."
Prasad, Anand R.; Buford, John F; Gurbani, K. Vijay (2011). Future Internet Services and Service Architectures. River Publishers. p. 309.
"There have been many mature open source SIP stack at present, such as Osip/Exosip, OPAL, VOCAL, etc. Among these SIP stacks, Osip/Exosip, which is small and fast, is most suitable for portable applications."
Sung, Wen-Pei; Kao, Jimmy C.M.; Chen, Ran (2012). Frontiers of Energy and Environmental Engineering. CRC Press. p. 314.