Cisco Systems OL-11591-01 manual Transcoders and Call Transfer, 12-20

Chapter 12 IP Video Telephony Configuration

Cisco Unified CallManager Configuration for IP Video Telephony

The regions include the following devices:

•Region A (Video)—All video enabled phones, including Cisco Unified Video Advantage

•Region B (SJC-Local)—All devices without video capabilities

•Region C (SJC-WAN)—All intercluster trunks

•Region D (DFW-WAN)—All intercluster trunks

•Region E (DFW-Local)—All devices without video capabilities

Table 12-22shows the regions matrix for SJC.

Table 12-22	SJC Regions Matrix
		Region A	Region B	Region C
Region A		G.711/384	G.711/384	G.711/384
Region B		G.711/384	G.711/384	G.729/384
Region C		G.711/384	G.729/384	G.729/384

Table 12-23shows the regions matrix for DFW.

Table 12-23	DFW Regions Matrix
		Region D	Region E
Region D		G.729/384	G.729/384
Region E		G.729/384	G.711/384

When an H.323 video endpoint in Region A calls through an intercluster trunk in Region B, only the G.711 codec is sent from SJC to DFW during the capabilities exchange process.

The call will arrive at DFW through an intercluster trunk in Region C and will then be routed to a device in Region D. Only the G.729 codec will be sent from DFW to SJC during the capabilities exchange process.

After the capabilities exchange process completes, the call will connect using the G.729 codec.

The Cisco Unified CallManager at SJC will invoke a transcoder between the H.323 video device and the intercluster trunk. The transcoder will transcode the call between the G.729 and the G.711 codecs.

Transcoders and Call Transfer

This section provides an overview of a call-transfer scenario that involves a legacy transcoder.

Note Cisco legacy transcoders (6608, CMM ACT, NM-HDV) currently do not support video pass-through. If a video call is sent through a transcoder, the call will become an audio-only call.

Before the call is transferred in this scenario, it proceeds as described for Scenario 2 in the “SIP Trunk Calls with Asymmetric Regions” section on page 12-19 . That is, an H.323 video endpoint with only G.711 capabilities in Region A calls a device in Region E through an intercluster trunk.

After the call is established, it is transferred by the device in Region E to a local video endpoint in Region F In this call-forward scenario, the call proceeds as follows:

	System Test Architecture Reference Manual for IP Telephony
12-20	OL-11591-01