Altigen ACM 6.5 Administration Manual page 376

Working with Servers in the Domain
3. Select an alternate server from the drop-down list.
4. Click Apply.
(After you click Apply, the current active server name will appear in the Current
Active Server box. This name is not editable.)
With the alternate server assigned, you can now configure individual extensions/groups
for redirection. See "Redirecting AltiGen IP Phones When a Server Is Down" on page 370.
If the alternate server assignment is removed from the configuration above, the
Note:
redirection configuration is removed from all extensions and workgroups to which
you assigned this feature (User button > Resolve tab).
If Native VM Integration with Microsoft Exchange 2007 is also configured, then
Note:
both the primary and alternate servers need to have the same dial plan configured
in the Microsoft Exchange server, so that users who have extensions flagged for
redirection can access their voice messages from both the primary and alternate
servers.
If the Primary or Alternate Server Is Behind NAT
When you configure the redirection feature for AltiGen IP phones, the primary server
sends the IP address of the primary and alternate servers to the IP phone. The IP phone
may run on the public or local network, and the primary server or alternate server may
run behind NAT. So to support a server behind NAT, the primary server sends the NAT
IP address or local private address according to the IP phone's IP address. If the IP
phone's IP address is in a local network for the server, the primary server sends the
private address, otherwise it sends the NAT address.
To configure for NAT,
1. In Enterprise Manager, click the Servers button > IP Networks tab.
2. In the NAT Support panel, check Enable SIP NAT Support.
3. Configure the NAT address.
4. In the IP Network panel, configure the IP range of the local network or public
network.
When Will Switchover Happen?
If the current active system is the primary server, switchover will happen under
one of the following conditions:
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MAXCS ACM 6.5 Administration Manual