Below is the answer my son received when he queried Intel about the ports their cameras and Intel Video phone software uses.
My son has broadband and a Linksys router. Me...I have broadband, no router but I am using Zone Alarm as my firewall.
The Intel(R) Video Phone uses the H.323 protocol to establish and conduct video calls. Per the H.323 protocol, only the first port number (1720) is static which is used to establish the connection. After the initial connection, a dynamically assigned TCP port number is negotiated for some more control data to be exchanged. Following that, dynamic User Datagram Protocol (UDP) ports (which range from 1024 to 65535) are negotiated for the actual exchange of audio and video. Rather than opening all ports on your router, please check with your router manufacturer to see if there is a setting or configuration you can make that will allow only H.323 traffic through your router. They may have updated router firmware that might provide H.323 support.
Well, I guess my son will have to tell his router (with its firewall) to leave ports 1024 through 65535 open and I will have to do the same with Zone Alarm. That's 64,511 open ports while only 1 is being used. Not exactly the situation one would like.
I suspect there is no practical way to leave just the one dynamic port in use open but if there is, would someone tell me how it can be done?