The main appeal of videoconferencing is to reduce business travel costs, but vertical applications such as distance learning are also driving this technology. There's also increasing interest in the T.120-based document conferencing packages bundled with many of these products. Programs such as Microsoft NetMeeting and White Pine's CUSeeMe provide whiteboards, document sharing, text chat, and file-transfer features. A common scenario on the low end: open up a session with video to see who you're talking to, then switch to audio conferencing and document sharing. You can also use these programs independently, but you'll need to coordinate a separate voice call if you want audio.

So far, single-user H.320 desktop systems have sold poorly, but lower-cost H.323 systems are growing in popularity. The early growth in H.323 systems has been in $100-to-$300 "Webcam" products that combine a low-cost monitor-top camera with a video capture card. Usually, these plug into the parallel port, but the latest systems claim better quality by using the higher-bandwidth USB port. This year, business-oriented H.320 systems have begun to add H.323 support backed up with hardware codec boards, and companies are buying gateways that link H.323 and H.320 users.

For video quality, see how the system reacts to sudden movement. For audio, check out its ability to handle overlapping conversations. Generally, quality improves with the presence of a hardware codec.

The latest systems offer a new H.263 video codec that delivers somewhat superior quality to the older H.261. Some H.320 systems also boost quality by supporting the new 384Kbps service, in which ISDN service providers combine three 128Kbps lines. Most H.323 systems support up to 768Kbps bandwidth over LAN, but on a multi-use LAN, however, the quality is generally inferior, and there's far less reliability. Faster computers help, but networks need to be upgraded with 100Mbps Ethernet switches and fast new routers. Beyond the experimentation stage, you'll also want to install gatekeeper software on your server to help manage H.323 traffic. The public Internet poses even great challenges to video, requiring use of emerging virtual private networks to achieve dependable business-quality (jitter-free 15fps) beyond the enterprise.

Helpful features to look for are picture-in-picture and still-frame capture, and the ability to adjust audio vs. video quality and image quality vs. frame rate. On the low end you may want a product that supports H.324 dial-up connections over 56Kbps modems. If you buy an ISDN system, look for one that lets you use the ISDN card for 128Kbps Internet access as well as conferencing.

More expensive group systems not only provide better quality, but also table-top controls and a superior camera equipped with zoom and remote access. Some systems offer voice-activated camera control, and others include built-in Web servers so you can easily schedule meetings and drag and drop documents off Web servers.

Look for a continuing drop in the price of group systems that support both H.320 and H.323 standards, as well as set-top devices that provide greater ease of installation. Also look for more systems with built-in MCU (multipoint control unit) servers to lower the price and improve the reliability of meetings between more than two sites. In the next year or two, DSL- and cable-modem-based H.323 systems should arrive with the potential for much greater video quality.

For a generation that grew up watching Kirk, Picard, Sisko, and Janeway hobnob with aliens over crystal-clear videoconferencing displays, the quality of today's videoconferencing technology is somewhat disappointing. Improvements in computer processing power and algorithms will help, but what's really missing is bandwidth -- and not just a fat pipeline, but a fat undisturbed pipeline.

In the networked enterprise, the infrastructure required for videoconferencing with the new H.323 standard is available today, but implementing it will cost you. You’ll need switched Ethernet to even start thinking about LAN-based video, and you’ll really want fast 100Mbps switches and smart routers that incorporate the Internet Engineering Task Force (IETF) standard called RSVP (Resource Reservation Protocol). While RSVP is not technically part of H.323, most H.323 products support it in order to improve the quality of conferencing sessions across a large intranet. Larger enterprise networks may also want to invest in ATM- or Gigabit-Ethernet backbones to link workgroups. First Virtual Corp. recently introduced an IP-to-ATM gateway, enabling ATM backbones to carry video traffic from Ethernet desktops.

Zippy network hardware alone won't solve the many glitches and latency problems typical of LAN videoconferencing. As H.323 usage increases over your network, you'll need to invest in gatekeeper software to help smooth the rough edges. This software can sit on any H.323 terminal, but is generally run as a server application. Typically, your first gatekeeper arrives as part of gateway software that translates between H.323 and H.320 ISDN connections.

Gatekeeper software eases conference setup by translating LAN aliases into IP or IPX addresses, and it manages bandwidth for optimal quality of service, meaning that streaming media such as videoconferencing can be guaranteed to pass over the network with at least a modicum of quality and consistency. H.323's bandwidth management tools include the User Datagram Protocol (which incorporates the IETF's IP Multicast and Real-Time Protocols) and the Real-Time Control Protocol, which handles quality of services issues. Most H.323 gatekeepers also support RSVP, which provides bandwidth reservation services over RSVP-compliant routers.

PictureTel's server-based LiveManager gatekeeper software, for example, let network managers tailor H.323 LiveLAN client calls based on the client's authorization level and computing capabilities. The manager can protect core network services by limiting the bandwidth that can be used by conferences, as well as prioritize the bandwidth for key conferences (for example, a scheduled meeting of the executive staff might receive greater priority than an ad-hoc session among lower-level employees). LiveManager can also monitor links with PictureTel’s H.320/H.323 gateway, LiveGateway, as well as keep track of activity running over an optional H.320 MCU (multipoint conference unit), which combines more than two conference participants in a single session. MCUs designed for H.323 (see below) generally include their own gatekeeper software.

If your company already has a number of legacy H.320-based group conferencing systems in-house, you can link them with your H.323 users via a gateway. However, to link them more directly, you may want to equip them with an H.323 option. RADVision, a leading vendor of H.323 protocol stacks and toolkits (along with companies such as DataBeam, Intel, and Lucent's Elemedia) recently introduced a new Video Interface Unit that connects legacy H.320 group systems to H.323 sessions.

Since it will take years for most LANs to upgrade their networking technology to support video, the fastest-growing application for H.323 gatekeeper software will be in handling the growing traffic in voice calls over the Internet. The IP-based voice or fax gateways that corporations are buying to save money on long-distance calls typically include H.323 gatekeepers that act as virtual PBX systems for monitoring traffic.

The recent explosion in voice-over-IP services is driving the H.323 standard more than videoconferencing. Adopted in January of 1998, H.323 version 2.0 boosted security, added support for ATM and RSVP, and incorporated multicasting support for broadcasting an H.323 feed to up to 1,000 users. But version 2.0 also added PBX-oriented call forwarding and call transferring features. Next year's version 3.0 places even greater emphasis on call management and IP telephony, with a special focus on inter-gatekeeper issues between different H.323 zones and circuit-switched PBX systems.

Since the standard (and the industry at large) placed the video cart before the talking horse, it will take years before gatekeeper software will be able to match sophisticated PBX technology. While H.323 has no significant competition on the video front, it’s being challenged by several standards for control of IP telephony. As demand grows for advanced H.323 gatekeeper software designed for use by ISPs and telephony carriers, IP telephony vendors may part ways with H.323 in favor of emerging IP voice standards such as IPDC (Internet Protocol Device Control) and SGCP (Simple Gateway Control Protocol).

It will take time before H.323 can implement the protocols needed to orchestrate thousands of calls that characterize carrier environments. "There's an issue of scalability with H.323," said Josh Adelson, product marketing manager for IP telephony at Brooktrout, a company that sells underlying H.323-based telephony technology to fax- and voice-server companies. At the same time, H.323's emphasis on video within a PC LAN setting may make it too complex for simple voice applications. The conferencing overhead also makes for a more complex and expensive client. "In a telco-class switching environment, H.323 is a little too verbose," says Adelson. "It goes through a number of steps in setting up the call. These other standards are more streamlined for voice."

The rift between the forces of IPDC/SGCP and H.323 tends to mirror the Wintel versus Java/NC battle. Microsoft and Intel support H.323 because it's a peer-to-peer standard that exploits a robust PC client. Most of the networking companies, on the other hand, including erstwhile Wintel collaborator Cisco, are pushing a thin client architecture that offers greater central control. ISPs and cable companies, which plan to roll out IP telephony services over the next few years, also tend to prefer this centralized approach.

The problem with switching to the new voice-specific standards, says George Kloak, RADVision's vice president for sales, is that customers will be unprepared in a few years when pipelines are capable of delivering high-quality videoconferencing. "The 60 companies we’ve sold H.323 technology to all have visions of implementing video alongside audio," says Kloak. "If you go for a cheaper client today, you'll have to do a forklift upgrade later." In the end, says Kloak, H.323 will adopt parts of the competing standards, especially in the development of a thin client.

Once you've invested in gatekeeper software for monitoring traffic and H.320/H.323 gateways for linking up with ISDN callers, demand will grow for multipoint conference units that can connect more than two callers. Most H.320 videoconferencing users still dial in to third-party MCU servers. While this approach is the most reliable, scheduling is inflexible, and the costs are high. Over the last year, there has been a new wave of lower-cost MCUs targeted at corporations that want to bring the MCU in house. The technology is still quite new and unreliable, especially when trying to implement continuous-presence conferencing in which up to four video signals are displayed simultaneously in a four-way split-screen format.

MCUs are also beginning to appear within videoconferencing systems themselves. Polycom just introduced the ViewStation MP, an H.320 group conferencing system that includes an MCU server. The $11,999 price tag is only $3,000 more than its ViewStation 512 system.

Theoretically, multipoint is easier (and cheaper) in an H.323 LAN setting, which is more naturally inclined to handle multi-user applications. H.323 multipoint servers make scheduling far more flexible than with circuit-switched systems, and they can also link more participants than an ISDN multipoint session, mixing video, audio, and T.120 conferencing callers. Most of the products can support between four and 24 interactive callers, depending on how many use video. With H.323's newfound IP Multicast support, White Pine's MeetingPoint Conference Server permits a single video caller to lecture and present documents to hundreds of nonvideo participants. It also provides continuous-presence multipoint, but only when all clients use White Pine's CU-SeeMe client software. The biggest cost savings come from the fact that H.323 multipoint conferences can be implemented solely in software as a server application. Aside from MeetingPoint, other software-based H.323 multipoint servers include DataBeam's NeT.120 Conference Server and PictureTel's 330 NetConference servers. VideoServer, an industry leader in MCUs, sells a more expensive hardware-based solution.