Address Translation

Jeff ChangWoo Son cwson at NISSI.NET
Thu Sep 13 17:41:53 EDT 2001


H.323 does not require that the call be cleared, so strictly speaking it is
an implementation decision. However, I would think that the best thing to do
would be to continue the call as an unregistered EP. There are a couple of
situations to consider, however.

1. The URQ could unregister specific aliases registered to the EP, in which
case it is still a "registered EP" and must therefore abide by the
requirements imposed on a registered EP, e.g., sending DRQ at the end of the

2. The URQ could unregister the EP itself (indicated by not specifying
aliases), in which case the EP simply becomes an unregistered alias. This
has no normative effect on a call, although I an implementation could clear
the call and still be compliant.

Here are the relevant passages:

7.2.2/H.323v4: "A Gatekeeper may cancel the registration of an endpoint by
sending an Unregister Request (URQ) message to the endpoint. The endpoint
shall respond with an Unregister Confirmation (UCF) message. The endpoint
shall attempt to re-register with a Gatekeeper prior to initiating any

ibid: "If the Gatekeeper sends a URQ message containing a list of alias
addresses, the endpoint shall assume that only those alias addresses are
unregistered. A URQ that contains no aliases shall indicate a request to
unregister the endpoint."

ibid: "An endpoint which is not registered with a Gatekeeper is called an
unregistered endpoint. This type of endpoint does not request admission
permission from a Gatekeeper and so cannot participate in admissions
control, bandwidth control, address translation and other functions
performed by the Gatekeeper."

Paul Long
ipDialog, Inc.

-----Original Message-----
From: Mailing list for parties associated with ITU-T Study Group 16
[mailto:ITU-SG16 at mailbag.cps.INTEL.COM]On Behalf Of Hans Viens
Sent: Thursday, September 13, 2001 1:16 PM
To: ITU-SG16 at mailbag.cps.INTEL.COM
Subject: URQ while a call is in progress

Hi Folks,

I was just wondering: if the gatekeeper sends a URQ to an endpoint that has
a call in progress, what should happen to this call ? Should it be cleared ?
It is possible to give me an indication where I could find this information
on the standard ?



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