1. From a user account that is a member of the RTCUniversalServerAdmins group (or has equivalent user rights), or is assigned to the CsAdministrator role, log on to any computer in your internal deployment.

2. Open a browser window, and then enter the Admin URL to open the Lync Server Control Panel. For details about the different methods you can use to start Lync Server Control Panel, see Open Lync Server Administrative Tools.

3. In the left navigation bar, click Network Configuration and then click Global.

4. On the Global page, click the Global configuration.

   Note:
   Only one network can be configured for any Microsoft Lync Server 2013 deployment, so there will never be more than one network configuration in the list. You cannot rename the Global configuration.

5. On the Edit menu, click Show details.

6. On the Edit Global Setting page, select the Enable call admission control check box, and then click Commit.

When you click Commit, you run a test of the configuration. The Edit Global Settings dialog box closes, returning you to the Global page. You will receive a warning if any errors or inconsistencies are discovered in your network configuration that will prevent it from working correctly (for example, if every region is not connected to every other region through an interregion route).

If you make changes to your network configuration, you can run the validation check again by opening the Global configuration and clicking Commit. You do not need to disable CAC first: leave the check box checked and click Commit. You can do this at any time without making any configuration changes.