주요 구조체 struct msg_start { int type; /* Type of the Message - Request/Response */ int len; /* length including delimiter */ union { struct { str method; /* Method string */ str uri; /* Request URI */ str version; /* SIP version */ int method_value; } request; struct { str version; /* SIP version */ str status; /* Reply status */ str reason; /* Reply reason phrase */ unsigned int /* statusclass,*/..