|struct ast_sip_body *||body|
|struct ast_variable *||headers|
|const char *||status_text|
Some of PJSIP's evsub callbacks expect us to provide them with data so that they can craft a response rather than have us create our own response.
Filling in the structure is optional, since the framework will automatically respond with a 200 OK response if we do not provide it with any additional data.