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Restricting bandwidth for video calls on 9971 devices


I've got a 9971 hanging of a relatively poor ADSL line and I need to restrict the bandwidth it uses when making a video. It works when it's configured to be in a location with high BW, but when I created a new Location and restricted the video BW to 400Kbps, I can't make video calls anymore. I then tried increments of 100Kbps until it began to work at 1000Kbps.

Am I missing something here? Can I set the video resolution for sending on 9971 devices.

Any pointers would be appreciated.



Re: Restricting bandwidth for video calls on 9971 devices


You should be setting the bandwidth parameter under REGION and not LOCATION. REGION will allow you to set the "Max Video Call Bit Rate" on a per call basis.

From the SRND document at, there is a very well written explanation on how the video bandwidth can be modified:

"The Video Bandwidth field accepts values in the range of 1 to 8128 kbps. However, to allow for compatibility with H.323 and H.320 videoconferencing devices, Cisco recommends that you always enter values for this field in increments of either 56 or 64 kbps. Therefore, valid values for this field include 112 kbps, 128 kbps, 224 kbps, 256 kbps, 336 kbps, 384 kbps, and so forth.

When the call speed requested by the endpoint exceeds the bandwidth value configured for the region, Unified CM automatically negotiates the call down to match the value allowed in the region setting. For instance, assume that an H.323 endpoint calls another H.323 endpoint at 768 kbps, but the region is set to allow a maximum of 384 kbps. The incoming H.225 setup request from the calling party would indicate that the call speed is 768 kbps, but Unified CM would change that value to 384 kbps in the outgoing H.225 setup message to the called party. Thus, the called endpoint would think that it was a 384-kbps call to begin with, and the call would be negotiated at that rate. The calling endpoint would show the requested bandwidth as 768 kbps, but the negotiated bandwidth would be 384 kbps.

However, if you set the Video Bandwidth to "None" in the region, Unified CM will either terminate the call (and send an H.225 Release Complete message back to the calling party) or will allow the call to pass as an audio-only call instead, depending on whether or not the called device has the Retry Video Call as Audio option enabled."

So to make a video call on a your poor ADSL line, you can update/create the Region to use a Video Bandwidth of 384kbps, the phone will be able to establish a Video call in VGA format at 15 fps, which is fairly good. At 625kbps, you are looking at 30fps. The change will affect any new calls and the configuration is not done on the handset and not just related to 9971 phones.

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