Unified Messaging Active Directory computer objects are created in the Computers container during the installation of the Unified Messaging server role. The Unified Messaging objects connect the telephony infrastructure of your organization and the Exchange 2010 Unified Messaging Active Directory networking environment and are a basic part of the Unified Messaging system. The Unified Messaging computer object created in Active Directory is a logical representation of a physical server on which the Unified Messaging server role is installed.

Important:
The Unified Messaging server must be a member of a domain before the Unified Messaging server role is installed so that a new Unified Messaging computer object can be created during the installation.

After the computer objects have been created, you can perform the procedures that are required to successfully deploy Unified Messaging on your network.

Note:
You can also apply Group Policy settings to the computer after the computer running Exchange 2010 is added to the domain.

A Unified Messaging server won't process incoming calls unless the operational state is set to enabled. By default, however, the operational status of the Unified Messaging server is set to enabled after installation. When its operational status is set to enabled, the Unified Messaging server can process incoming and outgoing voice calls and route the messages to the intended recipients in your Exchange organization.

Although the operational status of the Unified Messaging server is set to enabled after installation, the Unified Messaging server also maintains a status parameter that's used to control the operational status of the server. The status parameter lets you stop call processing so that the Unified Messaging server can be taken offline in a controlled way.

The operational status of the Unified Messaging server can be controlled by the enable and disable commands in the Exchange Management Console and the Exchange Management Shell. The following are the status modes for Unified Messaging servers:

• Enable   Process all incoming calls.
  
  
• Disable Immediately   Don't accept any new calls and drop all existing calls.
  
  
• Disable After Completing Calls   Don't accept any new calls but process all existing calls.
  
  

For more information about how to enable and disable a Unified Messaging server, see Enable Unified Messaging on Exchange 2010 and Disable Unified Messaging on Exchange 2010.

Even though the operational status of the Unified Messaging server is set to enabled after the Unified Messaging server role is installed, the server can't correctly process and route incoming calls to UM-enabled users until it's associated with at least one UM dial plan, and the UM dial plan is associated with at least one UM IP gateway. For more information about how to add a Unified Messaging server to a UM dial plan, see Add a UM Server to a Dial Plan.

For more information about UM IP gateways, see Understanding Unified Messaging IP Gateways.

After the Unified Messaging server is started, it locates all IP gateways that are associated with the UM dial plans and with the Unified Messaging server. To detect and identify any configuration changes on either UM dial plans or UM IP gateways, the Unified Messaging server will either register a change notification or check the configuration every 10 minutes.

If the UM IP gateway identifies any changes to the configuration, the Unified Messaging server reacts accordingly, and either starts using or stops using the appropriate IP gateways. After a Unified Messaging server is associated with a UM dial plan and is communicating with an IP gateway or IP Private Branch eXchange (PBX), you can run a set of diagnostic operations to verify the correct operation and connectivity.