Polycom realpresence 1800 Administrator's Manual page 667

When the flag is set to NO (default), if the Gatekeeper is not functioning, the Collaboration Server dials to
the endpoint using the endpoint's IP address configured in the IP Address field of the New
Participant/Participant Properties - General dialog box.
If no IP address is defined in the Participant Properties, the call will fail.
The method by which calls are dialed out to the endpoint is dependant on the flag value and the availability
of the Gatekeeper as summarized in the following table:
Determination of Method for Dialing an Endpoint by Flag and Gatekeeper Availability
Gatekeeper
Flag Value Available
NO NO
NO YES
YES NO
YES YES
Dial-in Calls
For Dial-in calls, direct IP dialing is enabled or disabled by the GK_MANDATORY_FOR_CALLS_IN and
system flag.
Polycom®, Inc.
Results
Dial out to endpoint IP Address bypassing the Gatekeeper.
Dial out to endpoint Alias Name using the Gatekeeper.
No dial out to endpoint.
Dial out to endpoint Alias Name using the Gatekeeper.
Gateway Calls
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