anchor.diff:                                     {'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">>}, {'from', <<"sip:alice@localhost">>},
  +                                   {'in-reply-to', <<"70710@saturn.bell-tel.com, 17320@saturn.bell-tel.com">>},
   
   
                                      {'content-length', <<"5">>}, {'via', <<"SIP/2.0/UDP localhost">>},
  
positive.code:                      "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",
                       "Expires: 213\r\nFrom: sip:alice@localhost\r\n",
  
                       "Content-Length: 5\r\nVia: SIP/2.0/UDP localhost\r\n",
                       "To: sip:bob@localhost\r\n"
  
negative.code:                    format('from', address(<<>>, <<"sip:bob@biloxi.com">>, [{'tag', <<"1928301774">>}]))),
       ?_assertEqual(<<"\"Bob Zert\" <sip:bob@biloxi.com>;tag=1928301774">>,
                     format('from', address(<<"Bob Zert">>, <<"sip:bob@biloxi.com">>, [{'tag', <<"1928301774">>}]))),
  
       % In-Reply-To
       ?_assertEqual([<<"70710@saturn.bell-tel.com">>, <<"17320@saturn.bell-tel.com">>],
                     parse('in-reply-to', <<"70710@saturn.bell-tel.com, 17320@saturn.bell-tel.com">>)),
       ?_assertEqual(<<"70710@saturn.bell-tel.com, 17320@saturn.bell-tel.com">>,
                     format('in-reply-to', [<<"70710@saturn.bell-tel.com">>, <<"17320@saturn.bell-tel.com">>])),
  
  
       % Max-Forwards
  