SIP协议学习总结
SIP对应关系
注册命令(信令)
REGISTER registers the address listed in the To header field with a SIP server
由UA向注册服务器请求To字段中带的SIP地址
200 ok or other error code from server
第1对命令
SUBSCRIBE request current state and state updates from a remote node.
NOTIFY used to notify a SIP node that an event which has been re[......]