between H.323 and SIP, translating between the two protocols to enable endpoints that only
support one of these protocols to call each other. In order to support H.323, the H.323 mode must
be enabled.

Using the Cisco VCS as an H.323 gatekeeper

As an H.323 gatekeeper, the VCS accepts registrations from H.323 endpoints and provides call
control functions such as address translation and admission control.
To enable the VCS as an H.323 Gatekeeper, you must ensure that H.323 mode is set to On (VCS
configuration > Protocols > H.323).

This is the default setting, so the VCS will work as an H.323 gatekeeper "out of the box",
without any other special configuration.

H.323 overview

H.323 endpoint registration

H.323 endpoints in your network must register with the VCS in order to use it as their gatekeeper.
There are two ways an H.323 endpoint can locate a VCS with which to register: manually or
automatically. The option is configured on the endpoint itself under the Gatekeeper Discovery
setting (consult your endpoint manual for how to access this setting).

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If the mode is set to automatic, the endpoint will try to register with any VCS it can find. It does
this by sending out a Gatekeeper Discovery Request, to which eligible VCSs will respond.

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If the mode is set to manual, you must specify the IP address of the VCS with which you wish
your endpoint to register, and the endpoint will attempt to register with that VCS only.