anchor.diff:      Headers = [{Name, Value} || {Name, Value} <- ReqHeaders,
                                   (Name =:= 'from' orelse Name =:= 'call-id' orelse
                                    Name =:= cseq orelse Name =:= 'via' orelse
  -                                 Name =:= 'to')],
  +                                 Name =:= 'to' orelse (Name =:= 'timestamp' andalso Status =:= 100))],
       #sip_response{status = Status,
                     reason = Reason,
                     headers = Headers}.
  
positive.code:     % custom reason
      Response2 = Response#sip_response{status = 201, reason = <<"Very Ok!">>},
  
      [% Check that all required headers are copied
       ?_assertEqual(Response, create_response(Request, 405)),
       ?_assertEqual(Response2, create_response(Request, 201, <<"Very Ok!">>))
       ].
  
  -spec create_ack_cancel_test_() -> list().
  
negative.code:                                 {'call-id', <<"987asjd97y7atg">>},
                                  {cseq, <<"986759 INVITE">>},
                                  {route, <<"<sip:alice@atlanta.com>">>},
                                  {route, <<"<sip:bob@biloxi.com>">>},
                                  {timestamp, <<"100 0.2">>}]},
  
      % (default reason)
      Response =
  