Thanks for your quick response.
We are not using any NAT. The office endpoint is on a static IP address and we are connected to our ISP using a 10mb each way fibre link. There is a Cisco 1820 router between the Tandberg system and the internet. It was supplied by our ISP and they say there is no filtering on the router. Its just providing the physical interface between our LAN and them. Our LAN is protected by a firewall but the VC bypasses that.
Conferencing between the Tandberg systems works fine and from the PVX software I was able to contact our site in China but not our two UK sites. I dont know much about the network connection in our China office but I believe its a standard DSL line and the ISP supplied router. The endpoint is a 550MXP.
Main Topics
Browse All Topics





by: foobar_666ukPosted on 2009-04-07 at 02:43:06ID: 24085383
If you are absolutely shure that this is not a firewall blocking ports then it sounds like the problem might be that you are using NAT? Are you using NAT at your offices - or are your Tandberg MXP's directly on the public internet?
If you are using NAT you will need to configure your Tandberg MXP to know about its external NAT address (Go to Admin Settings -> Network -> H323 Settings -> Advanced H323 Settings) in here you will see settings to switch NAT On or Off. Switch NAT on and then specify the external NAT address and this should then work.
The reason that NAT does not work with H323 video conferencing is because the endpoints embed the IP address into the IP payload, so that normal NAT functions will not work. But the settings above will tell the Tandberg endpoint to embed the correct external IP address into the Payload, therefore NAT will work.
Let me know how you get on