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VSX700A or Realpresence issue when calling RP Group 700

Occasional Contributor

VSX700A or Realpresence issue when calling RP Group 700


we've got to make a meeting from our old VSX7000A Release to a RP Group 700 from another organization, but when we test, they see us, but we don't have audio nor video.

Sometimes, after few minutes, the call establish fully, but it's not always the case.


I tried to call the test IP, also a RPG700, and I have exactly the same behavior. The signalisation allways works. Sometimes I have audio and video, many times I have not.


I was thinking that my VSX7000A was outdated, and I switched to a Realpresence Desktop we also have. I upgraded it on last version, We use it as a standalone H.323, without gatekeeper.


Behavior is almost the same, I have 3 call working, then 1 only with audio, then 7 call without video or audio, and then it works again.


It Make me think like the RTP session range is wrongly negotiated.

When the call works, RP desktop establish rtp session to port range 3230-3250.

When the call don't works, RP desktop establish rtp session to port range 3250-3304.

Sometimes it works on port arround 3250, but it never establish on port over 3260( it tried up to 3302), and It never fail on port under 3240.


I have tested my RP desktop directly on my DMZ network, with a WAN IP, without NAT, and I got the same behavior: 3 calls ok, 8 calls nok. during this test I was behind my firewall, but it never dropped a packet.


I also tested all tests terminals from Polycom:

Japan HDX 9006 works everytime

UK RealPresence Group 500 works everytime

US HDX 8000 and HDX 7000 works like the RealPresence Group 700: 3 Calls, then fails to have video during the next 8 calls, then working again for 3 calls.


Could be a problem with Polycom US firewall, but I doubt it.


Because of the 10 hours difference between my place and the place we have to call, organize real test with them is difficult. When they get to their office, I have already lived my since 3 hours.


This meeting is important, any help will be greatly appreciated.




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