Technical Support of Microsoft Lync on XenDesktop

As stated in Client Virtualization in Microsoft Lync 2010 (, republished by Microsoft in February 2012, delivery of the Lync 2010 client using XenDesktop and XenApp is “Supported” by Microsoft (see Table 2 on page 7). However, audio (voice chat) is not directly supported by Microsoft (see Table 3 on page 8) except through a desk phone using USB Redirection. Likewise, video chat is not directly supported by Microsoft. These statements are based on XenDesktop 4.0 and XenApp 6.0 (see Appendix A.1, page 12). As noted in the footnote on page 13, “XenDesktop 5 (which introduces webcam video compression as an alternative to USB redirection) was not tested.”

How do these statements impact Citrix customers who wish to deliver Microsoft Lync with voice and video chat functionality from XenDesktop 5.5/5.6 or XenApp 6.5?

In short, XenDesktop/XenApp delivery of Microsoft Lync, including voice chat and video chat, is fully supported by Citrix.

Microsoft does not directly support third-party products such as XenDesktop. In our experience, customers can expect “best effort” support from Microsoft but in some cases might be asked to duplicate a problem on a regular PC with no Citrix software installed.

Citrix supports the delivery of Microsoft Lync and other similar third-party Unified Communications clients and softphones from XenDesktop (including XenApp) to users of the Citrix Receiver through a variety of innovative technologies. These include the Optimization Pack for Microsoft Lync introduced with XenDesktop 5.6 Feature Pack 1 and XenApp 6.5 Feature Pack 1, and a set of generic HDX RealTime technologies which are compatible with Microsoft Lync and its predecessor, Office Communicator.

Highlights of the Optimization Pack for Microsoft Lync include:

  • Offload of all media processing from the Citrix server to the user device via the HDX RealTime Media Engine plug-in to the Citrix Receiver (initially available for Windows and Linux), thereby maximizing server scalability
  • Native support for Microsoft’s proprietary RTAudio and RTVideo codecs without transcoding
  • Up to 720p30 transmit and receive resolutions using H.264
  • Peer-to-peer media transport via RTP (only signaling goes over ICA)

Generic HDX RealTime technologies that are compatible with Microsoft Lync include:

  • Optimized-for-speech codec technology, featuring fast encode and low bandwidth utilization
  • Webcam Video Compression in the Citrix Receivers for Windows and Linux, offering excellent bandwidth efficiency and network latency tolerance
  • Jitter buffering in the Citrix Receiver for Windows to ensure smooth audio even when network latency is variable, and Echo Cancellation when using a microphone and speakers instead of a headset
  • Audio plug-n-play
  • Audio device routing (for example: ringtone can be directed to speakers but voice to a headset)
  • Multi-stream ICA transport for full QoS support
  • UDP/RTP audio option on XenDesktop VDI
  • DSCP packet tagging for RTP packets (Layer 3)
  • WMM tagging for Wi-Fi
  • Branch Repeater support for QoS and multi-stream ICA, including UDP

Furthermore, Citrix is committed to fully supporting the next release of Microsoft Lync, codenamed “Wave 15”.

Here’s the link to the original KB article.