Business-grade video conferencing can be handled over either ISDN lines (the switched digital network) or over an IP Network (LAN, WAN or Internet)
While IP networks are gaining popularity rapidly, over 50% of video conferencing is still handled on ISDN lines around the world. Equipment running on different types of networks can be connected through a Gateway.
The inherent advantage to using ISDN is security. With IP networks, security can be improved through encryption.
ISDN (Integrated Services Digital Network) lines are digital lines working over a switched network - like your regular telephone line - only much faster. The video conferencing standard is H.320.
IP Networks are quickly gaining popularity for H.323 conferencing. The primary advantage over ISDN is that there is no additional charge for long distance. This is particularly important with international video conferencing.
The challenge for IP Networks and video conferencing is to manage the latency and jitter so the quality of the picture is acceptable. For LANs and WANs, the necessary Quality of Service (QOS) can be managed by your IT Group, though it may require additional equipment and software upgrades.
While connecting over the Internet is possible, the picture and sound quality is not totally reliable for video conferencing.
Many companies are finding value in the services of Managed Network Providers. These companies provide Service Level Agreements on the network, guaranteeing QOS necessary for video conferencing. Even if you already have data networks between your various locations, it may be preferable to use an OVERLAY managed network arrangement for a combination of video conferencing, voice-over-IP, and overflow to the Internet.
For lowest-cost video conferencing on your computer and over the Internet, popular arrangements include Microsoft NetMeeting running on a Pentium III or higher with web camera and microphone, over broadband. However, the size and quality of the picture are limited, even with cable or ADSL connection to the ISP. Polycom also offers the low cost Via Video system ($550 each end), which is compatible with all H.323 standard equipment.