OSIP


oSIP is a free software library for VoIP applications implementing lower layers of Session Initiation Protocol. The library includes the minimal codebase required by any SIP application and offers enough flexibility to implement any SIP extension or behavior. Started in and published in, 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.

Software using oSIP