Global nua_invite (nua_handle_t *nh, tag_type_t, tag_value_t,...): If the INVITE request already contains a message body, SDP is not added. Also, if the response contains a multipart body, it is not parsed.
Global nua_notify (nua_handle_t *, tag_type_t, tag_value_t,...): If the Event is not given by application, stack uses the Event header from the first subscription usage on handle.
Global NUTAG_AUTOANSWER (x): If the re-INVITE modifies the session (e.g., SDP contains offer that adds video stream to the session), NUA auto-answers it if NUTAG_AUTOANSWER(0) has not been set on the handle. It accepts or rejects media based on the existing user SDP (set with SOATAG_USER_SDP(), for example). It should auto-answer only session refresh request and let application decide how to handle requests to modify the session.