QoS tagging of the media is performed by the Lync client itself, so it must be provisioned in a way that it understands what ports to use for each type of traffic. By default, no tagging is done and all traffic uses the port range 1,024–65,535. The Lync client supports using different port ranges for the following types of traffic and recommends a minimum number of ports for each modality. Using port ranges that are below the recommended minimums increases the chance for a media request to fail.
• Audio (20 ports required)
• Video (40 ports required)
• Application sharing (4 ports required)
• File transfer (4 ports required)
First, to enable separate port ranges for each media type, run the following command: