Videoconferencing behind NAT

Nowadays, they are having issues of configuring h323 devices behind NAT router, since h323 protocol uses dynamic ports over the internet, right? How can we fix this problem, especially setting up videoconferencing (ex:polycomview) behind SOHO routers? Take note: ports are forwarded already and firmware are upgraded as well? Have you encountered problem like this as well?

The NAT shouldn't cause trouble when it comes to dynamic ports, since NAT handles the ports being used internally. It is more likely that the problem is coming from the fact that the outside person cannot initiate an inbound connection through the NAT router. You could try and fix this by making the internal machine start the conversation. If that does not work, read the support for the video conferencing software you are using, they usually deal with stuff like this in the FAQ or forums / manuals.

I agree with sahirh. I had loads of trouble with a little router with NAT on it, and it worked outbound but not inbound. Try sitting down somewhere quiet and draw a diagram on paper, carefully, one step at a time, with all the addresses and eveything on it. You'll probably spot the problem that way

I don't know about video conferencing, but I was able to use the Linksys firewall and port forward to my Web Server and it seemed to work OK.

I guess the problem he's having is because the video conferencing might be using dynamic ports so he can't really use the port forwarding... dunno

I would assume that that would would be a problem on the public side of the firewall and not the private side, however.