1. Log on to the client computer as a member of the Administrators group.

2. Start the Lync Server Management Shell: Click Start, click All Programs, click Microsoft Lync Server 2010, and then click Lync Server Management Shell.

3. Get the current port ranges: At a command prompt, type the following command, and then press Enter:

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   Get-CsConferencingConfiguration

4. If you want to change the current settings, enable setting of port ranges: At a command prompt, type the following command, and then press Enter:

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   Set-CsConferencingConfiguration -ClientMediaPortRangeEnabled 1

5. Change the port range settings as necessary: At a command prompt, type the following command, including only the parameters that you want to change, and then press Enter:

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   Set-CsConferencingConfiguration -ClientAudioPort <beginning of port range> -ClientAudioPortRange <extent of port range, at least 20> -ClientVideoPort <beginning of port range> -ClientVideoPortRange <extent of port range, at least 40> -ClientAppSharingPort <beginning of port range> -ClientAppSharingPortRange <extent of port range, at least 4> -ClientFileTransferPort <beginning of port range> -ClientFileTransferPortRange <extent of port range, at least 4>

Clients must sign out and then sign in again for the changes to take effect.