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<TITLE>RE: On TD26 - Fast TCS and M/S negotiation in H.323v4</TITLE>
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<P><FONT SIZE=2>> Francois,</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> The UUIE _is_ a Q.931 IE, 5.8.6.2/Q.931 does not exclude this IE, and</FONT>
<BR><FONT SIZE=2>> neither H.225.0 or H.323 address the issue of how to handle a </FONT>
<BR><FONT SIZE=2>> UUIE--or any</FONT>
<BR><FONT SIZE=2>> other IE, for that matter--with invalid content, therefore </FONT>
<BR><FONT SIZE=2>> the behavior</FONT>
<BR><FONT SIZE=2>> defined in Q.931 is normative for H.323.</FONT>
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<P><FONT SIZE=2>An "invalid coding" for an information element does NOT include the content</FONT>
<BR><FONT SIZE=2>of a User-User information element. By definition, a Q.931 User-user IE can</FONT>
<BR><FONT SIZE=2>include whatever you feel like. A proper implementation will not reject a</FONT>
<BR><FONT SIZE=2>call because of the content of the User-user IE.</FONT>
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<P><FONT SIZE=2>> _All_ of Q.931 is an "ISDN thing," so what's your point?</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Finally, there is much in Q.931 that H.323 does not </FONT>
<BR><FONT SIZE=2>> reference, but that does</FONT>
<BR><FONT SIZE=2>> not invalidate the parts of Q.931 that H.323 references.</FONT>
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<P><FONT SIZE=2>H.323 does not use Q.931. H.225.0 recycled some of the messages (but not</FONT>
<BR><FONT SIZE=2>all of them). More importantly, it doesn't explicitly use the </FONT>
<BR><FONT SIZE=2>PROCEDURES of Q.931. There are some stringent timer requirements for</FONT>
<BR><FONT SIZE=2>example in Q.931 that not used use by H.323. The DISCONNECT and</FONT>
<BR><FONT SIZE=2>RELEASE messages are not even used. We are not even setting up </FONT>
<BR><FONT SIZE=2>a bearer channel in H.323 when doing a call setup.</FONT>
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<P><FONT SIZE=2>In summary, H.225.0 is NOT Q.931. </FONT>
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