Polycom MGC Administrator, Administrator'S Manual

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Chapter 7 - Configuring the Gateway
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gatekeeper returns the IP address of the destination endpoint to the gateway
(step 4 in Figure 7-3), which in turn transfers the call to the appropriate H.323
endpoint (step 5 in Figure 7-3).
Using this method, each configured endpoint has its own direct dial-in
number; therefore the gateway requires the use of many dial-in numbers (at
least as many as the number of H.323 endpoints). In addition, this method
requires the presence of a Gatekeeper for address translation (E.164 alias to
an IP address). If the H.323 endpoints were configured prior to the
configuration of the gateway, the system administrator has to change the
configuration of each endpoint and define a new alias according to the dial-in
numbers allocated to the gateway by the carrier.
Address Book
In the Address Book method, the gateway includes a conversion table in
which each DID number is assigned an alias or IP address of an H.323
endpoint. The carrier allocates the dial-in numbers to the MCU/Gateway, for
example, 1701 to 1800. In Figure 7-4, “System Configuration Using Address
Book”, the dial-in number 1721 is assigned to an H.323 endpoint whose alias
is 501.
Figure 7-4: System Configuration Using Address Book
Using this method, the H.320 endpoint dials a number that is comprised of the
gateway access number and the number that represents an entry in the
Address Book; for example, 9251721, where 925 is the gateway access
number and 1721 is the entry in the Address Book (step 1 in Figure 7-5, “Call