anchor.diff:      URI = sip_uri:format(Info#sip_hdr_info.uri),
       Bin = <<?LAQUOT, URI/binary, ?RAQUOT>>,
       append_params(Bin, Info#sip_hdr_info.params);
  +
  +%% 20.19 Expires
  +%% http://tools.ietf.org/html/rfc3261#section-20.19
  +process(fn, 'expires', _Ignore) -> <<"Expires">>;
  +process(p, 'expires', Bin) ->
  +    sip_binary:binary_to_integer(Bin);
  +
  +process(f, 'expires', Length) when is_integer(Length) ->
  +    sip_binary:integer_to_binary(Length);
  +
   
   %% .....
   process(pn, <<"v">>, _Ignore) -> 'via';
  
positive.code:                      "Content-Disposition: session\r\nContent-Encoding: gzip\r\n",
                       "Content-Language: en\r\nContent-Length: 5\r\n",
                       "Content-Type: application/sdp\r\nCSeq: 123 INVITE\r\n",
                       "Date: Sat, 13 Nov 2010 23:29:00 GMT\r\nError-Info: <sip:not-in-service-recording@atlanta.com>\r\n"
  
                       "Content-Length: 5\r\nVia: SIP/2.0/UDP localhost\r\nFrom: sip:alice@localhost\r\n",
                       "To: sip:bob@localhost\r\n"
  
negative.code:                                    {'content-language', <<"en">>}, {'content-length', <<"5">>},
                                     {'content-type', <<"application/sdp">>}, {'cseq', <<"123 INVITE">>},
                                     {'date', <<"Sat, 13 Nov 2010 23:29:00 GMT">>}, {'error-info', <<"<sip:not-in-service-recording@atlanta.com>">>},
                                     {'expires', <<"213">>},
  
  
                                     {'content-length', <<"5">>}, {'via', <<"SIP/2.0/UDP localhost">>},
  