Cisco Cisco TelePresence Video Communication Server Expressway
Appendix 4 – Known interoperating limitations
Cisco VCS Deployment Guide: Microsoft Lync 2010 and Cisco VCS X6.1
Page 60 of 81
Appendix 4 – Known interoperating limitations
Video codecs
If Lync client is used, then the video endpoints registered to the Cisco 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.)
H.263; this is the common video codec supported by endpoints and the Lync client. (The Lync client
does not support H.264.)
Video codec selection
When the Cisco VCS Control receives an H.323 call destined for Lync Server , the Cisco VCS must
interwork the call to SIP and generate a SIP INVITE to send to the Lync Server. Lync Server does not
support INVITES with no SDP – in other words, without a list of codecs that can be used for the call,
so the Cisco VCS Control must populate the SDP with a “pre-chosen” list of codecs from which the
Lync Server can select.
interwork the call to SIP and generate a SIP INVITE to send to the Lync Server. Lync Server does not
support INVITES with no SDP – in other words, without a list of codecs that can be used for the call,
so the Cisco VCS Control must populate the SDP with a “pre-chosen” list of codecs from which the
Lync Server can select.
The codecs offered and selected, therefore, may not reflect the best codecs that could have been
selected by the endpoints.
selected by the endpoints.
Joining a MOC conference (AV MCU)
Using a Lync client to invite a third party to join the call does not work whether the third endpoint is the
endpoint registered to the Cisco VCS Control or whether the endpoint registered to the Cisco VCS
Control is already in the call and another Lync client is introduced into the call.
endpoint registered to the Cisco VCS Control or whether the endpoint registered to the Cisco VCS
Control is already in the call and another Lync client is introduced into the call.
This is because when the Lync client invites a third party to join a call, the Lync client tries to create a
conference using Microsoft proprietary messaging (xml in SIP messages), and this is not supported by
standards-based video endpoints.
conference using Microsoft proprietary messaging (xml in SIP messages), and this is not supported by
standards-based video endpoints.
Neither Cisco VCS Control nor standards-based video endpoints support the Microsoft proprietary
signaling. Note, however use of Multiway™ on endpoints can join Lync clients into an ad hoc
conference. See the Cisco VCS Multiway™ deployment guide.
signaling. Note, however use of Multiway™ on endpoints can join Lync clients into an ad hoc
conference. See the Cisco VCS Multiway™ deployment guide.
Up-speeding from a voice call to a video call
Interworking a Lync client to an H.323 endpoint, the call will only up-speed from voice to video if the
up-speed request occurs before the endpoint sends a BRQ lowering the connection bandwidth.
up-speed request occurs before the endpoint sends a BRQ lowering the connection bandwidth.
Lync clients accessing Lync Server through Microsoft Edge
Server
Server
When Lync client registers to Lync Server through a Microsoft Edge Server, the SDP from Lync
contains Microsoft ICE candidates, and the non local candidate needs to be used.
contains Microsoft ICE candidates, and the non local candidate needs to be used.
This functionality is not supported in Cisco VCS X6.1. Calls made from an endpoint registered to Cisco
VCS to Lync should work, but calls made from Lync to an endpoint registered to Cisco VCS are likely
to result in audio and video on the endpoint registered to Cisco VCS, but no video or audio on Lync.
VCS to Lync should work, but calls made from Lync to an endpoint registered to Cisco VCS are likely
to result in audio and video on the endpoint registered to Cisco VCS, but no video or audio on Lync.
Microsoft Mediation Server
Using Lync Server
Calls to Microsoft Mediation Servers work from endpoints in the Cisco VCS Video Network for SIP
initiated calls, but do not work for interworked H.323 initiated calls (the mediation server does not
respond to the Cisco VCS INFO message, sent to check availability of the destination number).
initiated calls, but do not work for interworked H.323 initiated calls (the mediation server does not
respond to the Cisco VCS INFO message, sent to check availability of the destination number).