anchor.diff:  %% @doc Remove request information, if final response is received
   %% @end
   handle_final_response(ReqInfo, #sip_response{status = Status}) when Status >= 200 ->
  +    ok = tx_demonitor(ReqInfo),
       ok = delete(ReqInfo#request_info.id),
       error_m:return(ok);
   
  
positive.code: %% end
  do_cancel(false) ->
      {error, no_request};
  do_cancel(#request_info{cancel_tx = undefined, provisional = true} = ReqInfo) ->
      % start `CANCEL' transaction
      send_cancel(ReqInfo);
  do_cancel(ReqInfo) ->
  
negative.code: %% @end
  handle_provisional_response(ReqInfo, #sip_response{status = Status})
    when Status >= 100, Status =< 199,
         ReqInfo#request_info.cancel, not ReqInfo#request_info.cancelled ->
  
      % Start `CANCEL' tx, we got provisional response and have not started `CANCEL' tx yet
      ReqInfo2 = ReqInfo#request_info{provisional = true},
  