Cisco Cisco TelePresence Video Communication Server Expressway
Appendix 3: Interoperating capabilities and
limitations
limitations
Known interoperating capabilities
SIP and H.323 endpoints making basic calls
n
SIP and H.323 endpoints can make calls via VCS Control to Lync clients registered to Lync Server.
n
Lync clients registered to Lync can make calls to SIP and H.323 endpoints on VCS Control.
Upspeeding from a voice call to a video call
If a voice call is made from a Lync client to a video endpoint registered to VCS Control and then the video
button is selected to enhance the call to a video call, the video endpoint will correctly upspeed to video.
button is selected to enhance the call to a video call, the video endpoint will correctly upspeed to video.
When interworking a Lync client to an H.323 endpoint, the call will only upspeed from voice to video if the
upspeed request occurs before the endpoint sends a BRQ lowering the connection bandwidth.
upspeed request occurs before the endpoint sends a BRQ lowering the connection bandwidth.
Multiway generation of ad hoc conferences
Endpoints can join Lync clients into an ad hoc conference using the Multiway feature. When a Lync client is
transferred into a Multiway conference, the client will connect using audio only. The Lync user will then
manually have to enable video on the client after connecting to the conference.
transferred into a Multiway conference, the client will connect using audio only. The Lync user will then
manually have to enable video on the client after connecting to the conference.
Known interoperating limitations
Video codecs
If Lync 2010 is used, the video endpoints registered to the VCS Control must support H.263; this is the
common video codec supported by endpoints and the Lync client. (The Lync client does not support H.264.)
common video codec supported by endpoints and the Lync client. (The Lync client does not support H.264.)
The Lync 2010 client for Apple Mac OS X only supports RTVideo, no standards-based video codecs (H.263
or H.264). To make video calls between this client and standards-based video endpoints, a Cisco AM GW is
needed to transcode between RTVideo and H.263/H.264.
or H.264). To make video calls between this client and standards-based video endpoints, a Cisco AM GW is
needed to transcode between RTVideo and H.263/H.264.
Video codec selection
When the B2BUA receives a call with no SDP – that is, without a list of codecs that can be used for the call
(for example, a call that has been interworked from H.323), the B2BUA must populate the SDP with a “pre-
configured” list of codecs from which Lync can select, as Lync does not support INVITES with no SDP.
(for example, a call that has been interworked from H.323), the B2BUA must populate the SDP with a “pre-
configured” list of codecs from which Lync can select, as Lync does not support INVITES with no SDP.
The codecs offered and selected, therefore, may not reflect the best codecs that could have been selected
by the endpoints.
by the endpoints.
Changing the “pre-configured” SDP
The settings for the pre-configured SDP are configurable via the CLI only, using the xConfiguration
Zones Zone [1..1000] [Neighbor/DNS] Interworking SIP
Zones Zone [1..1000] [Neighbor/DNS] Interworking SIP
commands.
MXP endpoints
Video from MXP endpoints to Lync 2013 H.264 SVC is limited to 15fps (video with other endpoints is 30fps).
Microsoft Lync and Cisco VCS Deployment Guide (X8.1)
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Appendix 3: Interoperating capabilities and limitations