Draft White Paper for H.450.5 Call Park and Cal Pickup

Markku Korpi korpi at MCH.PN.SIEMENS.DE
Fri Aug 21 02:30:00 EDT 1998

On Thu, 20 Aug 1998 17:53:41 +0200 Olivier HERSENT wrote:
> Hi everyone,
> Some time ago, we had some brainstorming on roaming with H.323. One of the
> simplest ways to do it was that the roaming terminal would  send the ARQ,
> ...
> to the visited network GK (discovered my broadcast/multicast). This GK
> would recognize from the calling party alias that the terminal si from an
> external administation having an agreement with the visited administration.
> It would then forward the xRQs to the home gatekeeper of the terminal and
> get the xCFs in reply.
> This has many benefits :
> - The home GK knows where is the roaming teminal and can forward calls.
> - Any policy implemented at the home gatekeeper (restricted phone usage,
> etc ...) is still enforced in any visited domain
> - It is simple
> So roaming might be a good reason to forward xRQs ...  just my FF.02.

I agree that if I am a roaming user then I must be registered with my home
gatekeeper.  In addition to the reasons you give, my home gatekeeper is the only
element in the system which is authorised (by my company) to spend money on my
behalf when connecting to the PSTN via gateways.

However, I am not sure what is gained by my registering with the gatekeeper on
the visited network.  Surely an easier solution is for me to register directly
with my home gatekeeper directly whether I am at home or roaming?

In fact it may make it simpler, since I no longer need to multicast in order to
find the foreign gatekeeper, but can be configured with the address of my home
gatekeeper before leaving home (or can look it up from my AliasAddress in the
same way as I would if placing a call to it).

In addition to simplifying the model, this reduces the dependency on foreign
gatekeepers implementing the protocol correctly.



Andrew Draper - Principal Development Engineer - WAVE Software
Madge Networks, Wexham Springs, Framewood Road, Wexham, Berks.
mailto:adraper at dev.madge.com  phone:+44 1753 661329
pgp fingerprint D6 ED 72 4F 96 BB CA 2D  68 74 4C E0 CB B9 0B 3F

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