Backgroud:
1. Both H800 and Avaya MCU 5110 support up to H.264 1080P video.
2. Avaya MCU supports 720P video when conferencing with Avaya endpoints(XT1000)
3. H800 Called by(Or calling to) Avaya(RADVision) MCU 5110, the opened video channel can only max to 4CIF.
Analysis:
1. Both Avaya MCU and H800 support max to 1080P video
2. Avaya sends 4 CIF H.264 video TCS to H800. There is an additional field CustomMaxDPB in the capability parameters besides the typical CustomMaxMBPS and CustomeMaxFS.

Trouble shooting:
1. Double checked with the H.264 RFC, ISO/IEC 14496, and H.323 200912-E, the additional parameter CustomeMaxDPB indicates only the customized decode reference frames, it’s irrelevant to resolution and frame rate.
2. Asked FAE（张磊磊） to run more tests with the Avaya MCU by using different models of endpoints from different manufacturers.

Result:
Turned out the Avaya MCU could send different capabilities to different endpoint(by model, or by manufacturer):
To H800: 4CIF/25 fps
To Polycom RealPresence Desktop: SIF/25 fps
To Huawei TE40: 4CIF/25 fps

So, conclusion is it’s not an issue comes from H800, but a special process of Avaya MCU.
However, if we really need to conference with Avaya MCU with 720P video, we could consider send the H.323 protocol commands in disguise of Avaya endpoint which passed test in the previous tests.

Appendix 1: Test end point information
Avaya MCU 5110:
ProductID: RADVision ViaIp MCU,
VersionID: 7.7.0
Display information: RADVISION SCOPIA MCU (816150)
Avaya MT XT1000:
ProductID: RV XT1000
VersionID: V2.5.308 Mon Apr  2 17:35:51 2012
Display information: XT1000-81E