302 Chapter 9: Planning
its service account created in an accounts domain. Like any other server performing real-
time communications for end users, Unity is affected if it is in a resource domain that loses
its trust relationship to the accounts domain.
Unity can support Exchange 2000 in a Windows 2000 domain only. However, it is affected
directly by a misconfigured or unconfigured Windows 2000 site, or when installed into an
IP subnet that is not part of a Windows 2000 site. As stated in Chapter 10, Unity should be
installed in the same Windows 2000 site as the Exchange 2000 servers that it services. If
you deviate from this rule, expect to have delays with MAPI logins into those Exchange
servers.
Unity can support Domino R5 with DUCS, but the Unity server must be installed in a
Windows 2000 domain. This domain can be created by promoting the Unity server to a
DC in its own domain, or you can have Unity join an existing Windows 2000 domain.
Survey Your Network to Ensure That it Is Well Connected and Is Highly Available
The centralized call-processing model/centralized messaging model (see Chapter 10) sup-
ports remotely connected subscribers for voice messaging and unified messaging, as long
as there is ample bandwidth. Delays from streaming messages among Unity, its messaging
system, and the client also must be minimized.
Unity still can be affected—essentially, the entire telephony solution can be affected—if
service interruptions arise on any point in your network among Unity, the call-processing
functionality, and remotely connected clients.
Before deploying Unity, you should survey your network to discover any network compo-
nents, switches, routers, and gateways that have a history of service interruptions, excessive
traffic, and hardware problems. Address issues with any of these components, to ensure
their availability after Unity and an IP telephony solution are in place.
When you have identified problem network components and have addressed the issues
found, remember to monitor these components on a regular basis after Unity, CallManager,
and an IP telephony solution are in place.
Mailbox Store for Voice Messaging
If you plan a voice messaging-only deployment of Unity, either as an end solution to
replace an existing legacy voice-messaging system or as a stepping stone to unified
messaging, you will need to plan for a messaging infrastructure to support Unity. For Unity 4.0,
the only supported voice messaging-only configuration is Unity with Exchange 2000. So,
you must plan for a dedicated messaging infrastructure as a part of your Unity solution.
How do you design an Exchange 2000 messaging infrastructure to support Unity? You do
this the same way you would support a company-wide e-mail solution. Some differences

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