This document discusses a Javascript port of the JAIN SIP stack over websockets called Javascript SIP. It was created to allow re-using SIP-based infrastructure in webRTC applications by defining SIP over websockets. The core JAIN SIP classes have been ported by hand to Javascript while maintaining the same architecture, API and naming conventions. This provides a Javascript SIP stack that has been tested with early SIP over websockets implementations. Next steps include adding higher level APIs and optimizations to improve performance and support additional features like IMS/RCS profiles.