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HDX RealTime Optimization Pack 2.0 for Skype for Business on Citrix XenApp and XenDesktop VDI


Citrix and Microsoft recently revealed they have been working together on the Citrix 2.0 release of the XenApp/XenDesktop HDX RealTime Optimization Pack for Microsoft Skype for Business, which is now generally available.

Before this point, there were two options for Lync and VDI, the Microsoft Lync VDI Plugin and the HDX RealTime Optimization Pack 1.x or Microsoft Lync

  1. The Microsoft VDI Plugin supports virtualisation on Microsoft Remote Desktop Services, VMware Horizon View, and Citrix XenDesktop, but only on Windows based thin clients, there are some feature limitations and it isn’t supported on Office 365. The Microsoft VDI solution gave a complete native user experience.
  2. HDX RealTime Optimization Pack 1.x or Microsoft Lync worked on more types of endpoint, but relied on a plugin that essentially broke the media experience out of Lync.

For the new HDX 2.0 option, The joint Citrix and Microsoft goals for plugin were:

  • Comprehensive functionality, including audio-video and telephony features, when the Skype for Business client is hosted on Citrix XenApp or XenDesktop
  • Fully native user experience Skype for Business logo
  • Uncompromised quality of voice and video
  • Maximum XenApp/XenDesktop server scalability
  • Support for a broad range of devices and OS
  • Joint story from both vendors on roadmap and support

HDX RealTime Optimization Pack 2.0 delivers a native Skype for Business UI experience. And it adds numerous features to what was previously available in version 1.x such as:

  • Call Delegation
  • Response Groups and Team Call Groups
  • Voicemail integration
  • Automatic Join Meeting audio
  • Emoticons
  • Web Proxy support
  • Support for Click-to-Run (this comes from the blog post, but the KB says 2013/2015 MSI only at present)
  • Status icons (Connecting, Connected, etc.)
  • Active speaker identification

Some Limitations include:

  • No Location Services (Emergency Services, Set Your Location field, call routing based on location)
  • No Quality of Experience (QoE) metrics on media quality are not currently provided to the Microsoft SQL Server Reporting Service
  • No Gallery View multi-view video (HDX RealTime Optimization Pack displays the active speaker)
  • No Video Preview from the conversation window
  • No Convenience Recording
  • No Federation to the consumer version of Skype
  • Media Bypass is not supported
  • Client Support:
    • Microsoft Office Professional 2013 with Lync with at least the December 2015 Microsoft Office Public Updates. Citrix recommends having the latest updates. The client must be configured in native Skype for Business UI mode.
    • Microsoft Skype for Business 2015 stand-alone installer (which can be installed on top of Microsoft Office 2016)
    • Not Skype for Business 2016 MSI or C2R

SIP is all handed through Skype for Business, and media leverages Citrix’s multi-OS HDX RealTime Media Engine (RTME). RTME is currently available for Windows, Mac and Linux x86 devices, with equivalent functionality. The RTME provides a functional equivalent to the Skype for Business media stack, supporting all calling/conferencing scenarios, such as audio and video calling, hold, transfer, call forking and redirection, and active speaker conferencing. It supports up to 720p30 transmit and receive resolutions. And it is, of course, compatible with the Skype for Business protocols for networking, media encryption (SRTP/AES), firewall traversal (STUN/TURN/ICE) and bandwidth management. Audio and video are encapsulated through the HDX tunnel.

The RTME is a self-contained package with a much smaller footprint than the VDI Plug-in; it consumes about 120 MB of storage space on the user device.



HDX RealTime Optimization Pack 2.0 is compatible with XenApp 6.x/7.x and XenDesktop 7.x, and with Lync Server 2013 as well as Skype for Business Server 2015 and Skype for Business Online.

Citrix and Microsoft provide a joint support model for this solution. And each vendor can open trouble tickets with the other vendor as needed.

Citrix recommend HDX Premium thin clients for use with Skype for Business desktop video.

Video Demo from Citrix:


Citrix and Microsoft Unveil “v2” Solution for Skype for Business

HDX RealTime Optimization Pack 2.0

Skype for Business and Lync Delivery Feature Matrix

SfB Video Broadcast: Ep 9. VDI

Skype on XenApp: It’s a Snap! Looks and Acts Like Skype on a PC

About the author

Tom Arbuthnot

A Microsoft MVP and Microsoft Certified Master, Tom Arbuthnot is Principal Solutions Architect at Microsoft Collaboration specialists Modality Systems.

Tom stays up to date with industry developments and shares news and his opinions on his blog, Microsoft Teams Podcast and email list. He is a regular speaker at events around the world.


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Tom Talks Microsoft Teams and Microsoft 365 news and opinions