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How do I Integrate Lync 2013 with Cisco VTC?

There has been a lot of confusion surrounding the integration of Microsoft Lync 2013 with Cisco video conferencing systems. This post is intended to provide a general overview of the current Cisco / Lync 2013 interoperability landscape using Cisco infrastructure equipment. Let’s break up the topic into two sections: Signaling and Media.

Signaling – This is the control traffic that facilitates communication between two or more endpoints and allows calls to happen

  • Cisco endpoints such as MX, SX, and C-series codecs use H.323 for signaling and control.
  • Other Cisco Endpoints such as Jabber for desktop or mobile devices use Cisco SIP for signaling and control.
  • Both H.323 and Cisco SIP endpoints register to a VCS-Control gateway. This gateway allows H.323 devices and Cisco SIP devices to talk to each other.
  • Lync 2013 uses a Microsoft implementation of SIP; this is not the same as Cisco’s SIP.  Unfortunately the two protocols cannot natively communicate and therefore a direct call from Lync 2013 to a Cisco endpoint is not possible without a device to “translate” the signaling.
  • The device required to facilitate signaling is a VCS-Control with the Microsoft Interoperability Key; in essence the VCSc is deployed as a Lync Gateway. This VCSc Lync gateway is in addition to the core VCSc gateway mentioned above that your Cisco endpoints register to. The VCSc Lync Gateway communicates with the Lync Server and the core VCSc and the core VCSc in turn communicates with your Cisco endpoints.

Media – This is a separate session from Signaling that allows the media (video) to stream between endpoints.

  • With current Cisco firmware version TC6.3, Cisco endpoints now support H.264SVC for Media.
  • Lync 2013 now also supports H.264SVC, so Cisco endpoints can communicate with Lync 2013 for Media.
  • Note – This is a very simplified take on Media interoperability because there are different versions of H.264AVC/SVC. The basic point is that Lync 2013 and Cisco endpoints can now natively communicate media between devices.  

In summary, the key to “interoperability” between Cisco and Lync 2013 using Cisco infrastructure is to deploy a VCS Control gateway cluster made up of a Core VCSc and a VCS-c Lync Gateway.

Here are some other good things to know as things currently stand:

  • 720p 30fps can be supported in both directions
  • Presentation support can currently only go from Cisco to Lync
  • Lync 2013 users can be viewed on Cisco endpoints through the phonebook if TMS is deployed
  • Calls can be answered in either direction
  • There are certain restrictions on what the Lync Server and the VCSc can report to each other for Presence (i.e. not-available / available for call). If FindMe is deployed on the VCSc Lync gateway, enhanced Presence information is available on the Lync client.
  • Cisco MCUs do not support H.264SVC. In order to facilitate calls between H.264SVC devices and an H.264 MCU, transcoding would have to happen in a gateway (or another device). Details of solutions for this will follow in an upcoming post.

Video conferencing infrastructure and integration with Lync 2013 can be a very complicated topic. The above is intended only as a general overview of the technical concepts. If you have more specific questions about this integration, please feel free to contact us and speak with a consultant about your UC solution.

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