id(int,auto) rectime(int) x_context(string) s_method(string) s_cseq(string) a_callid(string) a_uuid(string) b_uuid(string) direction(int) x_via(string,null) x_vbranch(string) x_rr(string,null) y_rr(string,null) s_rr(string,null) x_uri(string) a_contact(string) b_contact(string) as_contact(string) bs_contact(string) x_tag(string) a_tag(string) b_tag(string) a_srcaddr(string) b_srcaddr(string) a_socket(string) b_socket(string) 
