Quality of service

Windows based XCC

QoS (Quality of Service) should be configured for softphone, AnyDevice or conference service connections. With the integrated XCC, this is configured in the operating system as follows.


The QoS configuration of an XCC outsourced on a LINUX satellite is done automatically.

This configuration determines the prioritisation with which packets are handled at the network card.

  1. Enter the command gpedit.msc via Start > Run.

  2. Create a new policy (e.g. XC_Softphone) or edit a policy previously created for Softphone under Computer Configuration > Windows Settings > Policy-based QoS:


  3. Specify a unique name for the policy. When specifying the DSCP value, we recommend setting 46. Then press Next.


  4. Enter the following path here under Only applications with this executable name: C:\Program Files\C4B\XPhone Connect Server\XCC\FreeSwitchConsole.exe


    If your XPhone Server is not in the default directory, you must change your installation directory here. Press Next.

  5. No changes are to be made here. Press Next:


  6. Select UDP for the protocol on which this QoS policy is applied. By default, the source port range 30000:33000 is entered here. If you have assigned a different range in the XPhone Connect Server in the XCC settings under System settings > Telephony & Meetings > Telephony > SIP > XCC, you must enter this:



With a tool for analysing network communication connections (so-called sniffer), such as Wireshark, you can check the settings you have made:




QoS for softphone in Wi-Fi according to IEEE 802.11e (WMM/WME).

The extension 802.11e of the Wi-Fi standard 802.11 allows the prioritisation of certain data packets in the wireless network (Quality of Service, QoS). It thus represents an important control function for voice transmission in WLAN (Voice over WLAN, VoWLAN). For technical details, see the IEEE 802.11 specification or the summary on Wikipedia.


QoS for VoWLAN is only available if both the client in the Wi-Fi and the access point support 802.11e.

  • Activate the option QoS according to 802.11e (also known as WMM or WME) for your Wi-Fi interface.

Virtualisation host

If you are operating the XPhone Connect Server on a Hyper-V image, the services listed below must be provided by Hyper-V for the virtual computer.

Open the Server Manager. To do this, enter under Start > Run > virtmgmt.msc.

Here you can display all virtual machines under Roles > Hyper-V > Hyper-V Manager. Select the required machine to display the menu on the right. Click on Hyper-V Settings under Actions. The settings dialogue opens:


Activate the required services under Administration > Integration Services, see above. | You can check whether the time synchronisation is set correctly by calling up the Windows command prompt in the server image with a right click on Start > Run > cmd or Windows key+R > cmd. | Change to the path C:\Windows\System32 and query the source of the system time with the command w32tm /query /sourceab. If the setting is correct, the result should be VM IC Time Synchronization Provider:


If the message Local CMOS Clock or a name of an NTP host (Network Time Protocol) is displayed, the services provided by the Hyper-V must be checked for correct settings, see above.

Client-side QoS Group Policy

In order to be able to give preferential treatment to the audio IP packets in the network, the Windows operating system comes with some options. These are either set directly in the Windows registry or can be distributed via group policy, the latter being the procedure recommended by C4B:

  1. Prioritising data traffic using DSCP

    The priority of outgoing network traffic can be defined via DSCP (Differentiated Services Code Point). According to the description in RFC 2474, DSCP allows values from 0 to 63 in the TOS field (Type of Service) of an IPv4 packet. Network routers use the DSCP value to classify network packets and determine the corresponding queue. A higher value indicates a higher priority of the packet. By default, the checkbox Specify DSCP value is selected and the value is set to 0.

  2. The following settings are recommended by C4B:

    • DSCP value: 46

    • Application name: C4B.XPhone.Commander.exe

    • Target Port Range: 30000:33000

References and sources:

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