osip实现RFC3261，全部用C语言实现，跨平台编译，小巧，简单，但是没有实现UA的能力；eXosip实现了UA的基本功能，是基于osip实现的。两个库唯一的缺点就是性能差了一些，不太适合服务器产品的开发，但是适合终端的开发。-oSIP realization of RFC3261, all using C language, cross-platform compiler, compact, simple, but did not achieve the UA s ability　eXosip to achieve the basic functions of the UA is based on the oSIP achievable. The only disadvantage of the two libraries is the poor performance of some, not at all suitable for server products, but suitable for terminal development.