Cisco Cisco TelePresence Video Communication Server Expressway
Appendix 6 – Setting default codecs for H.323 to SIP calls
Appendix 6 – Setting default codecs for H.323
to SIP calls
to SIP calls
Codecs to be offered
H.323 video calls typically do not provide codec information until after the call has connected. By
contrast, in SIP, the codec information exchange is typically started in the original INVITE. By default,
when interworking an H.323 call to a SIP call, Cisco VCS Control will start the SIP interworked call
with an INVITE which has no SDP, requesting that the called party initiates the codec offering.
contrast, in SIP, the codec information exchange is typically started in the original INVITE. By default,
when interworking an H.323 call to a SIP call, Cisco VCS Control will start the SIP interworked call
with an INVITE which has no SDP, requesting that the called party initiates the codec offering.
Microsoft OCS does not accept a SIP INVITE without an SDP.
Setting Empty INVITE allowed to Off in the Cisco VCS Control’s Edit Zone page
(VCS Configuration > Zones > OCS Neighbor) instructs Cisco VCS Control to put an SDP into the
INVITE, and therefore to propose a set of codecs to use.
(VCS Configuration > Zones > OCS Neighbor) instructs Cisco VCS Control to put an SDP into the
INVITE, and therefore to propose a set of codecs to use.
The default set of codecs to use are codecs supported by OCS; if, however, a change is required the
set of codecs proposed can be configured from the Command Line Interface.
set of codecs proposed can be configured from the Command Line Interface.
The default audio codec to offer is configured using:
xConfiguration Zones Zone [1..200] Neighbor Interworking SIP Audio
DefaultCodec:
<G711u/G711a/G722_48/G722_56/G722_64/G722_1_16/G722_1_24/G722_1_32/G722_1_48
/G723_1/G728/G729/AALCD_48/AALCD_56/AALCD_64/AMR>
<G711u/G711a/G722_48/G722_56/G722_64/G722_1_16/G722_1_24/G722_1_32/G722_1_48
/G723_1/G728/G729/AALCD_48/AALCD_56/AALCD_64/AMR>
… note only a single codec may be selected.
The default video codec to offer is configured using:
xConfiguration Zones Zone [1..200] Neighbor Interworking SIP Video
DefaultCodec: <None/H261/H263/H263p/H263pp/H264>
… note only a single codec may be selected.
The default bit rate to offer is configured using:
xConfiguration Zones Zone [1..200] Neighbor Interworking SIP Video
DefaultBitrate: <64..2048>
… note only a single bit rate may be selected.
The default resolution to offer is configured using:
xConfiguration Zones Zone [1..200] Neighbor Interworking SIP Video
DefaultResolution: <None/QCIF/CIF/4CIF/SIF/4SIF/VGA/SVGA/XGA>
… note only a single resolution may be selected.
Cisco VCS Deployment Guide: Microsoft OCS 2007 R1 and R2 and Cisco VCS X5.2
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