Previously, we talk about Microsoft Lync Phone edition, so, I would like to say something about how to improve the voice quality in this devices..
If you search, you will find the most common value used to DSCP in this case is 46(“Expedited Forwarding(EF)”).
According RFC 4594:
“1.5.3. Expedited Forwarding (EF)
The intent of Expedited Forwarding PHB [RFC3246] is to provide a building block for low-loss, low-delay, and low-jitter services. It can be used to build an enhanced best-effort service: traffic remains subject to loss due to line errors and reordering during routing changes. However, using queuing techniques, the probability of delay or variation in delay is minimized. For this reason, it is generally used to carry voice and for transport of data information that requires “wire like” behavior through the IP network. Voice is an inelastic “real-time” application that sends packets at the rate the codec produces them, regardless of availability of capacity. As such, this service has the potential to disrupt or congest a network if not controlled. It also has the potential for abuse.”
So, how can I check it? How can I change?
To check the current configuration, open PowerShell and run:
If you never change it, the default value is 40 for VoiceDiffServTag.
So, now to change this value to 46, use the follow command:
Set-CsUCPhoneConfiguration -VoiceDiffServTag 46 and then, run
Get-CsUCPhoneConfiguration to check the new value.
You can also change this value by Lync Server Control Panel. Go to Lync Server Control Panel, Clients, Device Configuration and the open the policy. Change the value of Voice Quality of Service (QoS).
To improve your environment, you can create differents policies to manage your devices and assign differents DSCP Values. Also, you can check here how to enable QoS in Lync Devices that are not based on Windows.