APC-1317 -> APC-1319 uploaded

[Pete Cordell]

Dear All,

The following documents have been uploaded to the FTP site:

APC-1317.doc
   Alternate Service Signalling:-
   The URL work has identified that there are a number of ways to
contact a
   user.  The URL work is trying to define mechanisms for determining
   different ways to contact a user.  However, this incurs delay as a
   result of requesting the information and if H.323 is the main method
for
   contacting a user it is sensible to try H.323 first, and then use
H.323
   to provide alternatives if the remote user is not available.

APC-1318.doc
   User Location Using H.225/Q.931 Signalling:-
   It has been commented in the past that the H.225/Q.931 signalling
does
   not allow for gatekeeper/proxy user location search algorithms.  This
is
   incorrect, and this proposal gives an example of how H.225/Q.931
   signalling can be used for this purpose.

APC-1319.doc
   Multicasting H.225/Q.931 Setup for User Location:-
   It has been mentioned in the past that H.323 does not allow much in
the
   way of multicast based user location.  This document describes how
this
   could be done with minor modification to H.323 by multicasting the
Q.931
   SETUP message.  The multicasted message contains a transport address
   which indicates where responding terminals should connect back to to
   take part in the call.  This type of feature is actually catered for
in
   Q.931 as the SETUP message is typically broadcast on to the S-Bus
(See
   T303 on sheet 4 of Figure A.3/Q.931, and Sheet 20).  Naturally the
   re-try strategy may need altering for the IP environment.
   The purpose of this is to show that it can be done, and to solicit
   opinion on whether it should be done, based on how useful it is
relative
   to the existing registration based method, and its impact on H.323
   signalling.

Regards,

Pete