Log on to the computer as a member of the RTCUniversalServerAdmins group, or as a member of the CsVoiceAdministrator, CsServerAdministrator, or CsAdministrator role. For details, see Delegate Setup Permissions.

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.

In the left navigation bar, click Voice Features and then click Unassigned Number.

On the Unassigned Number page, in the search field, type all or part of the name of the unassigned number range you want to delete.

In the list of number ranges, click the name that you want, click Edit, and then click Delete.

Click Commit all.