下图是来至 http://zhangwenjie.net 中的 PJSIP 开发指南

可惜在写此文的时候不能够访问！

从上图中可以看到 END POINT 是一个中心，有着非常重要的作用。而 PJSIP 官网中：

https://trac.pjsip.org/repos/doxygen/pjsip/html/modules.htm

也说到是一个 Very Core 部份，并且放到第一位！

我们必需要了解一下这部份！

官网是这样说的：

Detailed Description

SIP Endpoint instance (pjsip_endpoint) can be viewed as the master/owner of all SIP objects in an application. It performs the following roles:

• it manages the allocation/deallocation of memory pools for all objects.
• it manages listeners and transports, and how they are used by transactions.
• it receives incoming messages from transport layer and automatically dispatches them to the correct transaction (or create a new one).
• it has a single instance of timer management (timer heap).
• it manages modules, which is the primary means of extending the library.
• it provides single polling function for all objects and distributes events.
• it automatically handles incoming requests which can not be handled by existing modules (such as when incoming request has unsupported method).
• and so on..

看来是非常重要的一个模块！