In the video conference world ISDN service is still a great thing. The reason is that ISDN supports the traditional phone number format. It can be a challenge to have to dial and connect by IP address to other video conference equipment. It's really hard to remember all those IP addresses. Don't even get me started on what would happen to you once Ipv6 goes into effect. Newer units will typically have a phone book section that you can enter this information, so you only have to do it once. There are other solutions to. Video conference gateways are really great products. If you have one it can connect up to equipment using different protocols. For example one SIP device connecting to one H.323 device. It can also handle the connection info for a IP based video conference device. There by, allowing your video conference equipment to support both IP and ISDN connections. Although, video conference gateways are expensive. Plus, you would have to have both ISDN lines and standard IP connections to the gateway anyway. Instead of, having them directly conncted to each video conference equipment device.