Netgear CG814 cable modem/router, DLink DVC 1000 video conferencing system.
The DVC was sent to me and two colleagues by a company we all do contract work for. I've checked every setting I can think of. Dynamic IP address for the VCS, and the router sees it (I can ping it from my computer, and can ping my computer from it). I can ping the various IP addresses associated with my connection (the gateway, the gateway server, my ISP, the hosting service I use, etc). I've checked and re-checked all of the settings. I've gone from DHCP to Static IP and back. I've used the autodetect system and have configured the network settings manually, using every iteration I can find.
When I dial colleague A I get "unable to establish connection" -- along with a brief sound that is very reminiscent of a busy signal. When I dial colleage B the system just rings and rings -- like a telephone where nobody is home.
The company we work for has the same equipment, but doesn't have it set up. When we talked to their people, they say that B was able to connect to them, but they had a difficult time getting a connection in the other direction. They say "we finally did something" but since they don't have it connected (they moved into new digs a month or so ago, and haven't reconnected the equipment) they can't say what they did.
We're going nuts over this, not so much because we can't use it (there's always the telephone) but because we can't figure out why we can't figure it out.