San Jose meeting information
okubo at MXZ.MESH.NE.JP
Fri Feb 7 20:39:40 EST 2003
ECMA 333 defines the mapping functions for tunneling QSIG over H.323
It describes two scenarios, on-demand and semi-permanent.
In on-demand each new ISDN call is tunneled through a separate H.323 call.
In semi-permanent multiple ISDN calls can be tunneled through a single H323
10.2.4/H323 V4 describes the mechanism for tunneling ISDN protocols within
However, this only ssems to cover the on-demand scenario. It does not
include any procedures for the establisment of the additional RTP streams
that will be required to support multiple calls.
Obviously the existing logical channel procedures can be used to actually
open the channels - thats not the problem.
ECMA 333 states that the Channel ID IE in the tunneled messages should
contain the H.323 session id of the logical channel to be used for the audio
stream. This isn't a problem for on-demand, there is only one voice channel
and it uses the well-known session id 1.
However there are multiple active channels whenn using semi-permanent and
the problem is that the session ID is allocated by the H.323 master - what
happens if you want to originate a call from the H.323 slave - what do you
put in the tunneled ISDN SETUP message?
Is this actually covered anywhere or does it need something in H.323?
Is there any work in progress within the standards community to cover this
Any other commnents?
Principal Software Engineer
Vegastream, a division of Pace Micro Technology plc
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