We've been using our VSX 3000 for a number of years to connect to one other remote endpoint. Over the past several weeks we have been unable to receive video from that endpoint. We send the video OK and are able to send/receive the audio. I've connected to the Polycom test endpoint 22.214.171.124 and receive both audio and video. Does that confirm that the problem lies with the other endpoint (or their network) or would this not be a valid test?
If what you are saying is that when you test to the test number you are receiving both audio and video than the issue will be with the far end. Most likely a firewall issue, though a lot of times it also blocks the audio.
If you want an additional test site try 126.96.36.199, that is a heavily used test site but can confirm your original test.
if 188.8.131.52 doesn't answer (or is busy), try 184.108.40.206... I'm getting > 1600 calls per day so, be patient and try the call again..