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Configure the Number of Concurrent Calls on a UM Server


Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

You configure the number of incoming concurrent voice call connections that a Unified Messaging (UM) server accepts in Microsoft Exchange Server 2010. When you increase the number of concurrent connections on a Unified Messaging server, more system resources are required than if you decrease the number of concurrent voice call connections. Decreasing this setting is especially important on low-end, slower computers on which Unified Messaging is installed.


The range for the number of concurrent voice calls is 0 to 200. The default setting is 100.

Looking for other management tasks related to UM servers? Check out Managing Unified Messaging Servers.

Unified Messaging Permissions topic.

  1. In the console tree, navigate to Server Configuration > Unified Messaging.

  2. In the result pane, click to select the Unified Messaging server you want to set up.

  3. In the action pane, click Properties.

  4. On the UM Settings tab, in the Maximum concurrent calls text box, type the maximum number of concurrent voice calls.

  5. Click OK.

Use the Shell to set up the number of concurrent connections on a Unified Messaging server

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "UM server" entry in the Unified Messaging Permissions topic.

This example sets the number of incoming calls that can be accepted by a UM server named MyUMServer1 to 50.

Set-UMServer -Identity MyUMServer1 -MaxCallsAllowed 50

For more information about syntax and parameters, see Set-UMServer.

Other Tasks

After you configure the number of concurrent calls, you may also want toView the Number of Active Calls for a UM Server.

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