Polycom MGC Administrator Administrator's Manual page 425

MGC Administrator's Guide
Figure 7-11: IP-to-IP Call Flow Using Address Book
The gateway identifies #33 as an entry in the Address Book table and
translates this entry to alias 201 (step 5 in Figure 7-11). The gateway sends
the alias 201 to gatekeeper B for address translation (step 6 in Figure 7-11).
Gateway B returns the IP address of the endpoint to the gateway (step 7 in
Figure 7-11) using the parameters defined in the Session Profile 42. The
gateway calls endpoint 201 and connects the endpoint to the video conference
(step 8 in Figure 7-11).
In this method, all H.323 endpoints on the network can call any H.323
endpoint when two gatekeepers (one in each zone) are present. The H.323
endpoints must register with the gatekeepers using their numeric aliases (any
selected format). This enables gateway sessions over firewalls without
changing the organization network configuration or compromising its
security.
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