libosip2 implements the Session Initiation Protocol (SIP -rfc3261-) libosip2 is LGPL (COPYING). Please understand the licencing details before using it!
SIP is an IP telephony protocol made by the IETF. It is an effort to create a simple (telephony is never simple) and powerfull protocol for next generation telephony systems.
SIP is not just about telephony. It's much more that what you expect from phones. SIP means mobility, video, textual call informations, file exchange, instant messaging, presence support and much more!
As oSIP is LGPL, you still have the choice to implement propriatory application and link with oSIP. For the benefit of the community (and for your own benefit), please consider implementing your application in GPL.
